Explanation:
Volume of square pyramid = 1/3 base * height
so you will need to find the height ( MO ) using the sin function:
15 sin 38 = MO = 9.235 in
Now you need to find the measure of OD to calulate the base area
OD = 15 cos 38 = 11.82 and the entire diagonal of the base is two times this = 23.64 in
then, using the pythagorean theorem
23.64^2 = ab^2 + ab^2
ab = 16.716 in so base area = 16.716 x 16.716 = 279.42 in^2
Finally : Volume = 1/3 ( 279.42)(9.235) = ~~ 860 in^3