Question

The longest side of an acute triangle measures 30inches. The two remaining sides are congruent, but their length is unknown. What is the smallest possible perimeter of the triangle, rounded out the nearest hundredth

Answer 1

The two short sides must be longer than those required in an isosceles right triangle. The ratio of side length to hypotenuse length in a 45°-45°-90° triangle is 1 : √2. So, such a triangle requires side lengths of 30/√2 ≈ 21.213 inches. Its perimeter will be about

... (30 +21.213 +21.213) in = 72.426 in

Since the perimeter needs to be slightly longer than that for the triangle to be acute, the smallest possible perimeter is ...

... 72.43 in