The Moon is low in the sky shortly after sunset or before dawn; the bright part of its surface forms a beautiful creation. The two curves that form the boundary of the crescent resemble arcs of circles, and are often drawn that way. Assuming the Moon to be a perfect sphere, and the Sun’s rays to be parallel, are they arcs of circles?
Ref: Prof Ian Stewart’s Cabinet of Mathematical Curiosities.
More later,
Nalin Pithwa
Mathematics Hothouse 