# How is the distance between the earth and moon calculated?

6378 sin($\alpha$/2 ) sin$\theta$/2). $\alpha$ is parallax when Moon is seen, at same instant, from two places. $\theta$ is angle subtended at Earth's center by the join of the two locations..
Observe Moon;s center on a Full Moon night from two places 100 km apart for parallax $\theta$.. Then $\alpha$ = 100/6378 radian = 0.0156789 radian = 0.8983346 deg. The distance of the Moon then will be approximately 6378 sin(0.449167)/sin ($\theta$/2). The other way about , if the distance is known to be 384000 km, theta is nearly 0.1492 deg = 54", nearly.. .