HSPT Math : Geometry

Study concepts, example questions & explanations for HSPT Math

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Example Questions

Example Question #11 : Triangles

The hypotenuse of a right triangle is \(\displaystyle 39\) feet; it has one leg \(\displaystyle 36\) feet long. Give its area in square inches.

Possible Answers:

\(\displaystyle 38,880 \textrm{ in}^{2}\)

\(\displaystyle 43,120 \textrm{ in}^{2}\)

\(\displaystyle 42,120 \textrm{ in}^{2}\)

\(\displaystyle 77,760 \textrm{ in}^{2}\)

\(\displaystyle 101,088 \textrm{ in}^{2}\)

Correct answer:

\(\displaystyle 38,880 \textrm{ in}^{2}\)

Explanation:

The area of a right triangle is half the product of the lengths of its legs, so we need to use the Pythagorean Theorem to find the length of the other leg. Set \(\displaystyle c = 39 , b = 36\):

\(\displaystyle a^{2} = c^{2} - b^{2}\)

\(\displaystyle a^{2} = 39 ^{2} - 36^{2}\)

\(\displaystyle a^{2} = 1,521 - 1,296\)

\(\displaystyle a^{2} = 225\)

\(\displaystyle a = \sqrt{225} = 15\)

The legs have length \(\displaystyle 15\) and \(\displaystyle 36\) feet; multiply both dimensions by \(\displaystyle 12\) to convert to inches:

\(\displaystyle 15 \times 12 = 180\) inches

\(\displaystyle 36 \times 12 = 432\) inches.

Now find half the product:

\(\displaystyle A = \frac{1}{2} \cdot 180 \cdot 432 = 38,880\ in^{2}\)

Example Question #161 : Geometry

Which of the following is equal to the area of a rectangle with length \(\displaystyle 4.3\) meters and width \(\displaystyle 3.5\) meters?

Possible Answers:

\(\displaystyle 15,500 \textrm{ cm}^{2}\)

\(\displaystyle 155,000 \textrm{ cm}^{2}\)

\(\displaystyle 15,050 \textrm{ cm}^{2}\)

\(\displaystyle 150,500 \textrm{ cm}^{2}\)

Correct answer:

\(\displaystyle 150,500 \textrm{ cm}^{2}\)

Explanation:

Multiply each dimension by \(\displaystyle 100\) to convert meters to centimeters:

\(\displaystyle 4.3 \times 100 = 430\)

\(\displaystyle 3.5 \times 100 = 350\)

Multiply these dimensions to get the area of the rectangle in square centimeters:

\(\displaystyle 430 \times 350 = 150,500\textrm{ cm}^{2}\)

Example Question #2 : How To Find The Area Of A Trapezoid

Trapezoid

The above diagram depicts a rectangle \(\displaystyle RECT\) with isosceles triangle \(\displaystyle \Delta ECM\). If \(\displaystyle M\) is the midpoint of \(\displaystyle \overline{CT}\), and the area of the orange region is \(\displaystyle 72\), then what is the length of one leg of \(\displaystyle \Delta ECM\) ?

Possible Answers:

\(\displaystyle \sqrt {108}\)

\(\displaystyle \sqrt {54}\)

\(\displaystyle \sqrt {96}\)

\(\displaystyle 6\)

\(\displaystyle \sqrt {48}\)

Correct answer:

\(\displaystyle \sqrt {48}\)

Explanation:

The length of a leg of \(\displaystyle \Delta ECM\) is equal to the height of the orange region, which is a trapezoid. Call this length/height \(\displaystyle h\).

Since the triangle is isosceles, then \(\displaystyle CM = h\), and since \(\displaystyle M\) is the midpoint of \(\displaystyle \overline{CT}\), \(\displaystyle MT = h\). Also, since opposite sides of a rectangle are congruent, 

\(\displaystyle RE = CT = CM + MT = h + h = 2h\)

Therefore, the orange region is a trapezoid with bases \(\displaystyle h\) and \(\displaystyle 2h\) and height \(\displaystyle h\). Its area is 72, so we can set up and solve this equation using the area formula for a trapezoid:

 \(\displaystyle \frac{1}{2} (B + b)h = 72\)

\(\displaystyle \frac{1}{2} (2h + h)h = 72\)

\(\displaystyle \frac{1}{2} (3h )h = 72\)

\(\displaystyle \frac{3}{2}h^{2} = 72\)

\(\displaystyle \frac{3}{2}h^{2} \cdot \frac{2}{3} = 72 \cdot \frac{2}{3}\)

\(\displaystyle h^{2}= 48\)

\(\displaystyle h = \sqrt {48}\)

This is the length of one leg of the triangle.

Example Question #391 : Ssat Middle Level Quantitative (Math)

A trapezoid has a height of \(\displaystyle 25\) inches and bases measuring \(\displaystyle 24\) inches and \(\displaystyle 36\) inches. What is its area?

Possible Answers:

\(\displaystyle 600\; \textrm{in}^{2}\)

\(\displaystyle 1,500\; \textrm{in}^{2}\)

\(\displaystyle 864\; \textrm{in}^{2}\)

\(\displaystyle 900\; \textrm{in}^{2}\)

\(\displaystyle 750\; \textrm{in}^{2}\)

Correct answer:

\(\displaystyle 750\; \textrm{in}^{2}\)

Explanation:

Use the following formula, with \(\displaystyle B = 36,b = 24,h=25\):

\(\displaystyle A = \frac{1}{2} (B+b)h = \frac{1}{2} (36+24) \cdot 25 = 750\)

Example Question #51 : Geometry

What is the area of a triangle with a base of \(\displaystyle 12\) and a height of \(\displaystyle 3\)?

Possible Answers:

\(\displaystyle 36\)

\(\displaystyle 8\)

\(\displaystyle 18\)

\(\displaystyle 24\)

\(\displaystyle 21\)

Correct answer:

\(\displaystyle 18\)

Explanation:

The formula for the area of a triangle is \dpi{100} Area=\frac{1}{2}\times base\times height\(\displaystyle \dpi{100} Area=\frac{1}{2}\times base\times height\).

Plug the given values into the formula to solve:

\dpi{100} Area=\frac{1}{2}\times 12\times 3\(\displaystyle \dpi{100} Area=\frac{1}{2}\times 12\times 3\)

\dpi{100} Area=\frac{1}{2}\times 36\(\displaystyle \dpi{100} Area=\frac{1}{2}\times 36\)

\dpi{100} Area=18\(\displaystyle \dpi{100} Area=18\)

Example Question #52 : Geometry

Find the area of a square with side length 1.

Possible Answers:

\(\displaystyle 4\)

\(\displaystyle 1\)

\(\displaystyle 3\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle 1\)

Explanation:

To solve, simply use the formula for the area of a square. Thus,

\(\displaystyle A=s^2=1^2=1\)

Example Question #53 : Geometry

Find the area of a triangle with height 6 and base 3.

Possible Answers:

\(\displaystyle 18\)

\(\displaystyle 81\)

\(\displaystyle 9\)

\(\displaystyle 27\)

Correct answer:

\(\displaystyle 9\)

Explanation:

To solve, simply use the formula for the area of a triangle.

Given the height is 6 and the base is 3, substitute these values into area of a triangle formula.

Thus,

\(\displaystyle A=\frac{1}{2}Bh=\frac{1}{2}*6*3=9\)

Example Question #1833 : Hspt Mathematics

Square a

What is 60% of the area of the above square?

Possible Answers:

\(\displaystyle \frac{48}{5} \sqrt{2}\)

\(\displaystyle 38\frac{2}{5}\)

\(\displaystyle \frac{96}{5} \sqrt{2}\)

\(\displaystyle 19\frac{1}{5}\)

Correct answer:

\(\displaystyle 19\frac{1}{5}\)

Explanation:

The area of a square, it being a rhombus, is the product of the lengths of its diagonals. The diagonals are of the same length, so both diagonals have length 8, and the area of the square is

\(\displaystyle \frac{1}{2} \times 8^{2} = \frac{1}{2} \times 8 \times 8 = 32\).

60% of 32 is equal to 32 multiplied by \(\displaystyle \frac{60}{100}\), which is

\(\displaystyle 32 \times \frac{60}{100} = 32 \times \frac{3}{5} = 19\frac{1}{5}\).

Example Question #1834 : Hspt Mathematics

A circle has radius 12. Which of the following gives 40% of the area of this circle?

Possible Answers:

\(\displaystyle \frac{144 \pi}{5}\)

\(\displaystyle \frac{288 \pi}{5}\)

\(\displaystyle \frac{72 \pi}{5}\)

\(\displaystyle \frac{576 \pi}{5}\)

Correct answer:

\(\displaystyle \frac{288 \pi}{5}\)

Explanation:

The area of a circle with radius \(\displaystyle r\) is 

\(\displaystyle A = \pi r^{2}\).

The radius of the circle is\(\displaystyle r=12\), so the area is

\(\displaystyle A = \pi \cdot 12^{2} = 144 \pi\).

40% of this is 

\(\displaystyle 144 \pi \cdot \frac{40}{100} = 144 \pi \cdot \frac{2}{5 }= \frac{288 \pi}{5}\)

Example Question #54 : Geometry

A rectangle measures six feet in width and four and one-half feet in height. Give its area in square yards.

Possible Answers:

9 square yards

243 square yards

81 square yards

3 square yards

Correct answer:

3 square yards

Explanation:

Convert each dimension from feet to yards by dividing by conversion factor 3:

\(\displaystyle 6 \textup{ ft} \div 3 \textup{ yd/ft} = 2 \textup{ yd}\)

\(\displaystyle 4 \frac{1}{2} \textup{ ft} \div 3 \textup{ yd/ft} = \frac{9}{2} \textup{ ft} \div 3 \textup{ yd/ft}= \frac{3}{2} \textup{ yd}\)

Their product is the area in square yards:

\(\displaystyle 2 \textup{ yd} \times \frac{3}{2} \textup{ yd} = 3 \textup{ yd} ^{2}\).

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