Answer: Yes
Step-by-step explanation:
You can use the Pythagorean Theorm to find out of the three sides form a right angle. The Longest side is the Hypotenuse, and the two Smaller sides are the Legs of the triangle.
a² + b² = c²
15.9yd would be the hypotenuse since it's the longest side.
8.4² + 13.5² = 15.9²
70.56 + 182.25 = 252.81
252.81yd = 252.81yd
Since the two legs are equal to the hypotenuse, the lengths do form a right angle.