### All PSAT Math Resources

## Example Questions

### Example Question #1 : Right Triangles

A right triangle has one side equal to 5 and its hypotenuse equal to 14. Its third side is equal to:

**Possible Answers:**

171

14.87

9

12

13.07

**Correct answer:**

13.07

The Pythagorean Theorem gives us *a*^{2} + *b*^{2} = *c*^{2} for a right triangle, where *c* is the hypotenuse and *a* and *b* are the smaller sides. Here *a* is equal to 5 and *c* is equal to 14, so *b*^{2} = 14^{2} – 5^{2} = 171. Therefore *b* is equal to the square root of 171 or approximately 13.07.

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

Which of the following could NOT be the lengths of the sides of a right triangle?

**Possible Answers:**

5, 7, 10

8, 15, 17

14, 48, 50

5, 12, 13

12, 16, 20

**Correct answer:**

5, 7, 10

We use the Pythagorean Theorem and we calculate that 25 + 49 is not equal to 100.

All of the other answer choices observe the theorem *a*^{2} + *b*^{2} = *c*^{2}

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

Which set of sides could make a right triangle?

**Possible Answers:**

6, 7, 8

9, 12, 15

4, 6, 9

10, 12, 16

**Correct answer:**

9, 12, 15

By virtue of the Pythagorean Theorem, in a right triangle the sum of the squares of the smaller two sides equals the square of the largest side. Only 9, 12, and 15 fit this rule.

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

A right triangle with a base of 12 and hypotenuse of 15 is shown below. Find x.

**Possible Answers:**

5

4.5

3.5

5.5

4

**Correct answer:**

4

Using the Pythagorean Theorem, the height of the right triangle is found to be = √(〖15〗^{2 }–〖12〗^{2}) = 9, so x=9 – 5=4

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

A right triangle has sides of 36 and 39(hypotenuse). Find the length of the third side

**Possible Answers:**

33

12 √6

15

42

33√2

**Correct answer:**

15

use the pythagorean theorem:

a^{2} + b^{2} = c^{2} ; a and b are sides, c is the hypotenuse

a^{2} + 1296 = 1521

a^{2} = 225

a = 15

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

Bob the Helicopter is at 30,000 ft. above sea level, and as viewed on a map his airport is 40,000 ft. away. If Bob travels in a straight line to his airport at 250 feet per second, how many minutes will it take him to arrive?

**Possible Answers:**

3 minutes and 20 seconds

3 minutes and 50 seconds

4 hours and 0 minutes

2 hours and 30 minutes

1 hour and 45 minutes

**Correct answer:**

3 minutes and 20 seconds

Draw a right triangle with a height of 30,000 ft. and a base of 40,000 ft. The hypotenuse, or distance travelled, is then 50,000ft using the Pythagorean Theorem. Then dividing distance by speed will give us time, which is 200 seconds, or 3 minutes and 20 seconds.

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

A right triangle has two sides, 9 and *x*, and a hypotenuse of 15. What is *x*?

**Possible Answers:**

10

12

11

13

14

**Correct answer:**

12

We can use the Pythagorean Theorem to solve for *x*.

9^{2} + *x*^{2} = 15^{2}

81 + *x*^{2} = 225

*x*^{2} = 144

*x* = 12

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

The area of a right traingle is 42. One of the legs has a length of 12. What is the length of the other leg?

**Possible Answers:**

**Correct answer:**

### Example Question #1 : How To Find The Length Of The Side Of A Right Triangle

If and , what is the length of ?

**Possible Answers:**

**Correct answer:**

AB is the leg adjacent to Angle A and BC is the leg opposite Angle A.

Since we have a triangle, the opposites sides of those angles will be in the ratio .

Here, we know the side opposite the sixty degree angle. Thus, we can set that value equal to .

which also means

### Example Question #9 : How To Find The Length Of The Side Of A Right Triangle

Solve for *x*.

**Possible Answers:**

2

6

7

12

**Correct answer:**

6

Use the Pythagorean Theorem. Let *a* = 8 and *c *= 10 (because it is the hypotenuse)

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