Answer:
Side a = 35ft
Side b = 35ft
Side c = 20ft
Explanation:
The formula for the perimeter of a triangle = Side a + Side b + Side c
In an isosceles triangle, 2 sides are equal to each other.
So, Side a = Side b
In the question, we are told that:
The two equal sides are each 5 ft less than twice the length of the third side.
Hence,
a = 2c - 5
b = 2c - 5
P = 90ft
P = a + b + c
90 = 2c - 5 + 2c - 5 + c
Collect like terms
90 = 5c - 10
90 + 10 = 5c
100 = 5c
c = 100/5
c = 20
The length of the third side = 20ft
a = 2c - 5
= 2 × 20 - 5
= 40 - 5
= 35 ft
b =2c - 5
= 2 × 20 - 5
= 40 - 5
= 35 ft
Therefore,
Side a = 35ft
Side b = 35ft
Side c = 20ft