Question

How do you determine the measure of the central angle that is formed by an arc length of 4cm in a circle with a radius of 2.5cm?

Answer 1

The definition of radian is that it is equivalent to the angle subtended at the centre of a circle by an arc equal in length to the radius.

So:

`alpha_(rad)=(arc)/r`

`alpha_(rad)=4/2.5=1.6rad`.