How will measure the diameter of the Moon using parallax method?

Explanation

Let C be the centre of the Earth, A and B are two diametrically opposite places on the surface of the Earth as shown in figure. From A and B, the parallaxes `theta_(1) and theta_(2)` respectively of Moon M with respect to some distant star are determined with the help of an astronomical telescope.
Thus, the total parallax of the Moon subtended on Earth `angleAMB=theta_(1)+thea_(2)=theta`.

If `theta` is measred in radians, then `theta=(AB)/(AM), AM~~MC`.
`theta=(AB)/(MC) or M.C=(AB)/(theta)`
Knowing the values of AB and `theta`, teh distance MC of Moon from the Earth can be calculated.