During a total solar eclipse,the moon almost entirely covers the sphere of the sun. Write the relation between the distances and sizes of the sun and moon.

(N/A) Consider the diagram provided.
Let $D_{me}$ be the distance of the moon from the earth.
Let $D_{se}$ be the distance of the sun from the earth.
Let $R_m$ be the radius of the moon and $R_s$ be the radius of the sun.
Since the moon covers the sun,the angular diameter $\theta$ subtended by both at the earth is the same.
Using the formula for angular diameter,$\theta = \frac{\text{diameter}}{\text{distance}}$,we have:
$\theta = \frac{2R_s}{D_{se}} = \frac{2R_m}{D_{me}}$
Dividing both sides by $2$,we get:
$\frac{R_s}{D_{se}} = \frac{R_m}{D_{me}}$
Therefore,the relation is:
$\frac{R_s}{R_m} = \frac{D_{se}}{D_{me}}$
This shows that the ratio of the sizes of the sun and moon is equal to the ratio of their respective distances from the earth.