Question

The height of a triangle is 9 feet less than twice the length of its base. Its area is 9 square feet. What are the dimensions of its base and height? Recall that the area of a triangle is 1/2bh.

Its base is ____ feet and its height is ____ feet.

Answer 1

Explanation:

If we let the length of the base be b, then the height is 2b-9.

This means that (1/2)(b)(2b-9)=9

b(2b-9) = 18

2b^2 - 9b = 18

2b^2 - 9b - 18 = 0

(2b+3)(b-6)=0

b = -3/2 or b= 6 (disregard b = -3/2 as distance is positive)

This means b =6, and thus the height is 2(6)-9=3.