What are radians and what are they used for?

Radians are a unit of measurement. They work in the same way that we use ounces to measure mass or metres to measure length. Radians are however used to measure angles, the more common unit of measuring angles you would be familiar with are degrees and therefore radians are simply an alternative measurement to these. In exam questions, it is very common to have questions on both degrees and radians and therefore it is crucial to know both of these units. It is usually common to see radians more commonly than degrees in subject areas such as physics or engineering. The unconventional trick with radians is that they are usually expressed as a multiple of π e.g. 2π.  (However you can still have 1 radian or decimal radians e.g. 2.14343... radians). To convert from from degrees to radians you need to know that the general is 2π radians is equal to 360 degrees. E.g. a circle must have 2π radians. By some simple division, you can then also work out that π radians is equal to 180 degrees and π/2 radians is 90 degrees and so on.