Question

The triangle shown at the right is isosceles. That is, it has two sides of an equal length. The third side is 30 m shorter than twice the length of each congruent side. The perimeter is 570 m. Find the length of each side.

Answer 1

We know that perimeter of the triangle its a+b+c=570
Moreover we know that:
a=b
b=b
c=2b-30
Finally we can substitute into our formula
b+b+2b-30=570 
4b-30=570        /+30
4b=600           /:4
b=150 - its a and b side
c=2*b-30
c=300-30
c=270 - its c side