In: Physics
By using arc-length, determine the angular size of the Moon as seen from Earth. Also, determine the angular size of the Sun as seen from Earth.
show full steps please

In the figure, the angular size of the object is 

Therefore the angular size is
. ............. (1)
For small angles, this can be approximated to

But I will use equation(1) which will give the slightly more accurate result.
where d is the diameter of the object and D is the distance from the observer on earth to the object
a) For Moon

and distance from earth to the moon is

Therefore the angular size of the moon is

Also, note that

Therefore the angular size of the moon is

b) For Sun

Therefore

In arcseconds,
