Question

The sun is over head at the Equator (0⁰) on march 21^st; what will be the angle of the sun at Addis Ababa (9⁰N)

Answer 1

The angle is

$$\theta=\arcsin\frac{D_{ES}}{\sqrt{D_{ES}^2+(9/360·2\pi R_E)^2}},\\\space\\ \theta=\arcsin\frac{149.6·10^6}{\sqrt{(149.6·10^6)^2+(9/360·2\pi ·6378)^2}}=90°.$$