Question

Find the distance from the eye at which a coin of 2 cm diameter should be held so as to cancel the full moon whose angular distance is 31 minutes

Answer 1

Step-by-step explanation:

30 arc minutes is half a degree. Multiply tangent to that that by the Moons average distance 384400 km and you get about 3354 in diameter. Since the Moon varies in distance, this is an approximation and the true diameter is closer to 3474 km.

So you have 347400000 cm versus 2.2 cm times a distance of 38440000000 cm: 38440000000 * 2.2 / 347400000 = 243 cm.