Question

The first side of a triangle is 7cm less than twice the second side. The third side is 4cm longer than the first side. The perimeter is 80cm. Find the length of each side of the triangle.

Answer 1

Given:

First side(A): 2B - 7

Second side(B): B

Third side(C): B + 4

Plug in values:

A + B + C = 80

2B - 7 + B + B + 4 = 80

If you look at the coefficients only, you can rewrite the equation like this:

2B + B + B - 7 + 4 = 80

This means that 4B - 7 + 4 = 80

=4B - 3 = 80

= 4B = 80 + 3

B = 83/4, so you can either write B as 83/4 or as 20.75.

Checking your work:

A: 2(20.75) - 7 = 34.5

B: 20.75

C: 4 + 20.75 = 24.75

34.5 + 20.75 + 24.75 = 80cm.

Hope this helped.