Question
Mathematics Question on Trigonometric Functions
The large hand of a clock is 42cm long. How much distance does its extremity move in 20 minutes?
A
88cm
B
80cm
C
75cm
D
77cm
Answer
88cm
Explanation
Solution
The large hand of the clock makes a complete revolution in 60 minutes. ∴ Angle traced out by the large hand in 20 minutes (of time) =60360∘×20=120∘=180120π radian =32π radian Hence, the distance moved by the extremity of the large hand =(42)×32π=88cm. (∵l=rθ)