An isosceles triangle has two sides of equal length. The length of the third side is 5 ft less than twice the length of one of the equal sides. Find the length

Question

I dont understand please help me out

Answer 1

Here's what we know:

P = a + b + c (Perimeter of a triangle is the sum of all three sides)

a = b (two of the sides are the same length)

c = 2a - 5 (the third side is 5 less than twice one of the others sides)

P = 31

 

We have the values for variables, so plug them in:

31 = a + a + 2a - 5

Simplfy:

31 = 4a - 5

Now to isolate a. Start by adding 5 to both sides:

31 + 5 = 4a - 5 + 5

36 = 4a

Divide by 4:

36 / 4 = 4a / 4

a = 9

 

Now that you know a, you can find b and c from here.