Intermediate Geometry : How to find the perimeter of a rhombus

Study concepts, example questions & explanations for Intermediate Geometry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #42 : Rhombuses

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

Possible Answers:

\(\displaystyle 50\)

\(\displaystyle 52\)

\(\displaystyle 40\)

\(\displaystyle 60\)

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 #212 : Intermediate Geometry

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

Possible Answers:

\(\displaystyle 32.81\)

\(\displaystyle 28.84\)

\(\displaystyle 39.67\)

\(\displaystyle 20.36\)

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 #213 : Intermediate Geometry

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 #43 : Rhombuses

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

Possible Answers:

\(\displaystyle 65.29\)

\(\displaystyle 50.44\)

\(\displaystyle 59.37\)

\(\displaystyle 55.61\)

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 #215 : Intermediate Geometry

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 #216 : Intermediate Geometry

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

Possible Answers:

\(\displaystyle 40\)

\(\displaystyle 45\)

\(\displaystyle 50\)

\(\displaystyle 55\)

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 #217 : Intermediate Geometry

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

Possible Answers:

\(\displaystyle 58\)

\(\displaystyle 62\)

\(\displaystyle 54\)

\(\displaystyle 66\)

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 #218 : Intermediate Geometry

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

Possible Answers:

\(\displaystyle 188.03\)

\(\displaystyle 174.22\)

\(\displaystyle 152.36\)

\(\displaystyle 144.22\)

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 #41 : Rhombuses

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

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

\(\displaystyle m \angle BCD = ?\)

Possible Answers:

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

\(\displaystyle 110^{\circ }\)

\(\displaystyle 130 ^{\circ }\)

\(\displaystyle 105^{\circ }\)

\(\displaystyle 155^{\circ }\)

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,

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

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

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

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

Learning Tools by Varsity Tutors