What is a Radian?
In this post, we will be defining and using radian measure and understand its relationship with degree measure, as a part of the Prelim Maths Advanced course under the topic Trigonometric Functions and sub-part Radians. We will convert between the two measures, using the fact that 360^{o} = 2\pi radians and recognise and use the exact values of sin(\theta), cos(\theta) and tan(\theta) in both degrees and radians for integer multiples of \frac{\pi}{6} and \frac{\pi}{4} . A radian is the angle of the sector with the radius as the arc length, it is a pure measure of a circle as it is the radius of a circle laid on the circumference, and a lot of ratios can be effectively represented from this.
To convert from degrees to radians you: \times \frac{\pi}{180}
To convert from radians to degrees you: \times \frac{180}{\pi}
Introduction to radians
The following three videos introduce you to the definition of a radian and allows you to understand how to convert between the two measures.
Part 1
Part 2
