f.2 maths very difficult

Angle travelled by the minute hand in 42 minutes = 42/60 x 360 = 252 degree
so distance travelled = 2p(11) x 252/360 = 15.4p cm. (p = pi.)
For minute hand travelled 42 minutes, hour hand travelled 5/60 x 42 = 3.5 ' minutes' which equals to 3.5/60 x 360 = 21 degree.
so distance travelled by the hour hand = 2p(6) x 21/360 = 0.7p cm.
so difference = 15.4p - 0.7p = 14.7p cm. = 46.2 cm ( 3 sig. fig.)

時鐘的時針移了:
6x2x(42/60)x(pi)
=8.4pi

時鐘的分針移了:
11x2x(42/60)x(pi)
=15.4pi

15.4pi-8.4pi
=7cm







2010-05-30 21:16:50 補充：
Sorry,The answer is 7pi cm!