What angles do lateral faces make with the base plane of a rectangular pyramid with base edges of 10 m and 16 m and with lateral edges of 18 m each? Please help!

Answer 1

The vertex of the pyramid lies above a point which is 5m from the long sides of the base, and 8m from the short sides.
So, we can compute the height of the pyramid using
h^2 + 5^2+8^2 = 18^2
Now, using h, we can find the angles using either
tanθ = h/8 or tanθ = h/5