By the process of elimination I believe that the angle the sun makes with the building is the vertex angle. If that is our reference angle, we have the hypotenuse as 150 and we are looking for the side opposite the reference angle, which we will call x. Therefore, the sin ratio is the one we need, as sin is equal to the side opposite over the hypotenuse. 
and 150 sin(75) = x. That gives you an x value of 144.89, first choice above.