Question

The length of a pendulum is 70 cm and it describes an arc of length 88 cm when swings. The angle subtended by the arc at the centre is ______.

विकल्प

• 36°

• 70°

• 72°

• 80°

Answer 1

The length of a pendulum is 70 cm and it describes an arc of length 88 cm when swings. The angle subtended by the arc at the centre is 72°.

Explanation:

Given:

Length of pendulum (radius of circle) = 70 cm 

Length of arc = 88 cm

Formula for arc length:

l = rθ

where θ is in radians.

Calculate θ:

`θ = l/r`

= `88/70`

= 1.2571 radians

Convert radians to degrees:

`θ = 1.2571 xx 180/π`

= 1.2571 × 57.2958

= 72°