Question

The tip of a 15-inch wiper blade wipes a path that is 36 inches long. What is the angle of rotation of the blade in radians to the nearest tenth?

2.4 radians
1.2 radians
2.8 radians
0.4 radians

Answer 1

The length of the arc is a fraction of the circumference of the circle depending on the length of the radius and the intercepted angle. This can be calculated through the equation,

L = (2πr) x (θ /360)

where L is the length of arc, r is the radius, and θ is the intercepted angle in terms of degrees.

Substituting the known values to the equation,

36 = (2π)(15) x (θ / 360)

We translate the equation to find the value of θ,

θ = (36)(360) / 2π(15)

The value of θ is equal to 137.51°.

This can be coverted to radians through the equation below,

θ (in radians) = 137.51° x (2π rad / 360°) = 2.4 rad