PSAT Math : How to find the height of a triangle

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #121 : Geometry

A triangle has a base of 5 cm and an area of 15 cm. What is the height of the triangle?

Possible Answers:

5 cm

3 cm

None of the above

6 cm

1.5 cm

Correct answer:

6 cm

Explanation:

The area of a triangle is (1/2)*base*height. We know that the area = 15 cm, and the base is 5 cm, so:

15 = 1/2 * 5 * height

3 = 1/2 * height

6 = height

Example Question #93 : Triangles

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In the figure above, AB = AD = AE = BD = BC = CD = DE = 1. What is the distance from A to C?

Possible Answers:

\displaystyle \sqrt{2}

\displaystyle 2

\displaystyle \sqrt{3}

\displaystyle \frac{1}{2}

\displaystyle 1

Correct answer:

\displaystyle \sqrt{3}

Explanation:

Trapequi2

Trapequi3

Trapequi4

Example Question #94 : Triangles

A triangles has sides of 5, 9, and x\displaystyle x. Which of the folowing CANNOT be a possible value of x\displaystyle x?

Possible Answers:

6\displaystyle 6

3\displaystyle 3

5\displaystyle 5

7\displaystyle 7

4\displaystyle 4

Correct answer:

3\displaystyle 3

Explanation:

The sum of the lengths of the shortest sides of a triangle cannot be less than the third side.

3 + 5 = 8 < 9, so 3 can't be a value of x.

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