Question

The height of a triangle is 5 m less than its base. The area of the triangle is 42 m². Find the length of the base.

7m
8 m
11 m
12 m

Answer 1

D, 12m

Explanation:

Answer 2

12 m

Explanation:

Area of a triangle is:

A = ½ bh

Given that h = b - 5 and A = 42:

42 = ½ b (b - 5)

84 = b² - 5b

0 = b² - 5b - 84

0 = (b + 7) (b - 12)

b = -7, 12

The length of the base can't be negative, so b = 12 m.