坡度與斜面數學題2(15分)

Actually, the key point of this question is to find out the difference of the height of building B and that of building A, let the difference be "z" metres

First, find out the height of building B:

let the height of building B be "y" metres

y/35 = tan 58
y = tan 58 x 35

So the difference z = 70 - y
z = 70 - tan 58 x 35

Finally, extend the vertical line of building B upwards and draw a horizontal line from building A to building B to form a triangle, you should then realize:
(assumed the angle that you have to find as "O")

z/ 35 = tan O
(70 - tan 58 x 35)/ 35 = tan O

I think you would be able to find O then.