Find the distance along an arc on the surface of the earth that subtends a central angle of 1 minute. (1 minute = 1/60 degree) This is a nautical mile. Note that the radius of the Earth is 3960 miles and there are 1760 yards in a mile. Express your answer in both miles and yards.

Answer 1

s = r*theta
s = 3960 * 1/60 * pi/180 = 1.15mi
1.15mi * 1760yd/mi = 2027yd

Answer 2

how are the following relations true? S(theta + pi/2) = C(theta) and C(theta + pi/2) = -S(theta)?