Intermediate Geometry : Rhombuses

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #41 : Quadrilaterals

Find the perimeter of a rhombus that has an area of \displaystyle 102 and a diagonal of \displaystyle 12.

Possible Answers:

\displaystyle 45.96

\displaystyle 43.37

\displaystyle 47.20

\displaystyle 41.62

Correct answer:

\displaystyle 41.62

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(102)}{12}=17

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{12}{2}=6

\displaystyle \text{Half diagonal 2}=\frac{17}{2}=8.5

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{6^2+8.5^2}=\sqrt{108.25}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{108.25}=41.62

Make sure to round to \displaystyle 2 places after the decimal.

Example Question #42 : Quadrilaterals

Find the perimeter of a rhombus that has an area of \displaystyle 150 and a diagonal of \displaystyle 15.

Possible Answers:

\displaystyle 60

\displaystyle 50

\displaystyle 52

\displaystyle 40

Correct answer:

\displaystyle 50

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(150)}{15}=20

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{15}{2}=7.5

\displaystyle \text{Half diagonal 2}=\frac{20}{2}=10

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{7.5^2+100^2}=\sqrt{156.25}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{156.25}=50

 

Example Question #43 : Quadrilaterals

Find the perimeter of a rhombus if it has an area of \displaystyle 48 and a diagonal of \displaystyle 8.

Possible Answers:

\displaystyle 28.84

\displaystyle 32.81

\displaystyle 39.67

\displaystyle 20.36

Correct answer:

\displaystyle 28.84

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(48)}{8}=12

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{8}{2}=4

\displaystyle \text{Half diagonal 2}=\frac{12}{2}=6

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{4^2+6^2}=\sqrt{52}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{52}=28.84

Make sure to round to \displaystyle 2 places after the decimal.

Example Question #44 : Quadrilaterals

Find the perimeter of a rhombus if it has an area of \displaystyle 152 and a diagonal of \displaystyle 16.

Possible Answers:

\displaystyle 49.68

\displaystyle 47.01

\displaystyle 52.33

\displaystyle 45.26

Correct answer:

\displaystyle 49.68

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(152)}{16}=19

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{16}{2}=8

\displaystyle \text{Half diagonal 2}=\frac{19}{2}=9.5

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{8^2+9.5^2}=\sqrt{154.25}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{154.25}=49.68

Make sure to round to \displaystyle 2 places after the decimal.

Example Question #45 : Quadrilaterals

Find the perimeter of a rhombus if it has an area of \displaystyle 187 and a diagonal of \displaystyle 17.

Possible Answers:

\displaystyle 50.44

\displaystyle 65.29

\displaystyle 59.37

\displaystyle 55.61

Correct answer:

\displaystyle 55.61

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(187)}{17}=22

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{17}{2}=8.5

\displaystyle \text{Half diagonal 2}=\frac{22}{2}=11

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{8.5^2+11^2}=\sqrt{193.25}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{193.25}=55.61

Make sure to round to \displaystyle 2 places after the decimal.

Example Question #46 : Quadrilaterals

Find the perimeter of a rhombus if it has an area of \displaystyle 228 and a diagonal of \displaystyle 19.

Possible Answers:

\displaystyle 61.22

\displaystyle 71.85

\displaystyle 65.03

\displaystyle 69.81

Correct answer:

\displaystyle 61.22

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(228)}{19}=24

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{19}{2}=9.5

\displaystyle \text{Half diagonal 2}=\frac{24}{2}=12

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{9.5^2+12^2}=\sqrt{234.25}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{234.25}=61.22

Make sure to round to \displaystyle 2 places after the decimal.

Example Question #47 : Quadrilaterals

Find the perimeter of a rhombus if it has an area of \displaystyle 96 and a diagonal of \displaystyle 12.

Possible Answers:

\displaystyle 45

\displaystyle 55

\displaystyle 50

\displaystyle 40

Correct answer:

\displaystyle 40

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(96)}{12}=16

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{12}{2}=6

\displaystyle \text{Half diagonal 2}=\frac{16}{2}=8

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{6^2+8^2}=\sqrt{100}=10

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4(10)=40

 

Example Question #48 : Quadrilaterals

Find the perimeter of a rhombus that has an area of \displaystyle 210 and a diagonal of \displaystyle 20.

Possible Answers:

\displaystyle 66

\displaystyle 58

\displaystyle 54

\displaystyle 62

Correct answer:

\displaystyle 58

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(210)}{20}=21

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{20}{2}=10

\displaystyle \text{Half diagonal 2}=\frac{21}{2}=10.5

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{10^2+10.5^2}=\sqrt{210.25}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{210.25}=58

Example Question #49 : Quadrilaterals

Find the perimeter of a rhombus if it has an area of \displaystyle 1200 and a diagonal length of \displaystyle 40

Possible Answers:

\displaystyle 144.22

\displaystyle 174.22

\displaystyle 152.36

\displaystyle 188.03

Correct answer:

\displaystyle 144.22

Explanation:

13

Recall the following properties of a rhombus, as shown by the figure above: The diagonals of a rhombus are perpendicular and they bisect each other. Thus, if we know the lengths of the diagonals, we can use the Pythagorean theorem to find the length of a side of the rhombus.

Recall how to find the area of a rhombus:

\displaystyle \text{Area}=\frac{(\text{diagonal 1})(\text{diagonal 2})}{2}

Since we are given the length of one diagonal and the area, we can find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(\text{Area})}{\text{diagonal 1}}

Plug in the given values to find the length of the second diagonal.

\displaystyle \text{diagonal 2}=\frac{2(1200)}{40}=60

Now, notice that the halves of each diagonal make up a right triangle that has the side length of the rhombus as its hypotenuse.

\displaystyle \text{Half diagonal 1}=\frac{40}{2}=20

\displaystyle \text{Half diagonal 2}=\frac{60}{2}=30

Now, use these half values in the Pythagorean Theorem to find the length of the side of a rhombus.

\displaystyle \text{Side of Rhombus}=\sqrt{20^2+30^2}=\sqrt{1300}

Finally, recall that a rhombus has four equal side lengths. To find the perimeter, multiply the length of a side by four.

\displaystyle \text{Perimeter of rhombus}=4\sqrt{1300}=144.22

Make sure to round to \displaystyle 2 places after the decimal.

Example Question #50 : Quadrilaterals

Given Rhombus \displaystyle ABCD and diagonal \displaystyle \overline{ BD}

\displaystyle m \angle ABD = 25 ^{\circ }

\displaystyle m \angle BCD = ?

Possible Answers:

\displaystyle 110^{\circ }

\displaystyle 130 ^{\circ }

\displaystyle 155^{\circ }

\displaystyle \textup{The question cannot be answered from the information given}

\displaystyle 105^{\circ }

Correct answer:

\displaystyle 130 ^{\circ }

Explanation:

The rhombus referenced is below:

Rhombus

A diagonal of a rhombus bisects the angles of the rhombus at its endpoints. Therefore, since \displaystyle m \angle ABD = 25 ^{\circ }, it follows that \displaystyle m \angle DBC = 25 ^{\circ } as well. By angle addition,

\displaystyle m \angle ABC = m \angle ABD + m \angle DBC = 25^{\circ }+ 25^{\circ } = 50^{\circ }.

As consecutive angles of a rhombus (and, consequently, of a parallelogram), \displaystyle \angle ABC and \displaystyle \angle BDC are supplementary - that is, their measures total \displaystyle 180^{\circ }. Therefore,

\displaystyle m \angle ABC + m \angle BCD = 180^{\circ }

\displaystyle 50 ^{\circ } + m \angle BCD = 180^{\circ }

\displaystyle 50 ^{\circ } + m \angle BCD - 50 ^{\circ } = 180^{\circ } - 50 ^{\circ }

\displaystyle m \angle BCD = 130 ^{\circ }

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