2025 · Q76
A pendulum swings through 30° and the arc length is 55 cm. Taking π=22/7, what is the length of the pendulum?
Elementary MathematicsCircles
- A90 cm
- B100 cm
- C105 cm
- D110 cm
Explanation
Arc length = r*theta with theta in radians: 30 degrees = pi/6. So 55 = r*(pi/6), giving r = 330/pi = 330*7/22 = 105 cm. Forgetting to convert degrees to radians is the standard error.