The isosceles triangle is missing so i have attached it.
Answer:
Length of unknown side = 5p + 6
Step-by-step explanation:
In isosceles triangle, two of the sides are equal. In the attached triangle, we see that one of the equal sides is given as 5p + 3.
Thus,the second equal side is also 5p + 3.
Now, perimeter of a triangle is the sum of the three sides.
We have two sides and let the third side be denoted as x.
Thus;
Perimeter = (5p + 3) + (5p + 3) + x
We are given perimeter = 15p + 12
Thus;
(5p + 3) + (5p + 3) + x = 15p + 12
10p + 6 + x = 15p + 12
Rearranging, we have;
x = 15p - 10p + 12 - 6
x = 5p + 6
