Question

A 20-foot ladder is leaning against a tree. The bottom of the ladder is 12 feet away from the bottom of the tree. Approximately how high up the tree does the top of the ladder reach?
A. 2.4 feet

B. 6 feet

C. 9.2 feet

D. 16 feet

Answer 1

Remark

This is just the Pythagorean Theorem

Formula

a^2 + b^2 = c^2

Givens

a = 12

b = ??

c = 20

Solve

12^2 + b^2 = 20^2         Square 12 and 20

144 + b^2 = 400             Subtract 144 from both sides.

b^2 = 400 - 144          

b^2 = 256                      Take the square root of both sides

sqrt(b^2) = sqrt(256)

b = 16 <<<< Answer

Answer 2

Using the Pythagorean Theorem we can solve.

20^2 - 12^2 = X^2

400 - 144 = X^2

256 = X^2

X = √256

X = 16 feet.

The answer is D.