Answer:
Third side is 15cm. Perimeter is 37cm.
Step-by-step explanation:
In a triangle sum of two sides is always greater than third side. Two sides of a isosceles triangle are equal.
So if the third side is 7cm
7+7=14cm which is less than 15 cm.
hence third side is 15 cm as
15+15=30cm which is greater than 7cm
15+7=22cm which is greater than 12cm
then
perimeter=15+7+15=37cm
