Answer:
(C)72.4 in
Step-by-step explanation:
Given an acute triangle in which the longest side measures 30 inches; and the other two sides are congruent.
Consider the attached diagram
AB=BC=x
However to be able to solve for x, we form a right triangle with endpoints A and C.
Since the hypotenuse is always the longest side in a right triangle
Hypotenuse, AC=30 Inches
Using Pythagoras Theorem

Therefore, the smallest possible perimeter of the triangle
Perimeter=2x+30
=2(21.21)+30
=42.42+30
=72.4 Inches (rounded to the nearest tenth)