Answer:
Choice A, 40 in.
Explanation:
Though its not clear here, I'm going to assume the missing side is the hypotenuse. If not, the my answer is probably not right then.
In order to find the hypotenuse, we can use Pythagorean Theorem which is:
a^2+b^2=c^2
C in this equation is the hypotenuse, while a and b are the legs of the right triangle.
Now, lets just plug it in:
32^2+24^2=c^2
1024+576=c^2
1600=c^2
40 = c
From this the hypotenuse is 40, it would be Choice A.