What are radians, why can't we just use degrees?

When you start your A Level, radians can seem very daunting because you've never seen them before and pi seems a very confusing number to use in relation to angles. But trust me, if you embrace radians they will become your friend as they make calculations a lot simpler. For example, if you want to find the arc length for angle θ, in degrees that would be 2pir*(θ/360) - whereas if you use radians it is simply rθ. Not to mention there is no way to use integration or differentiation in degrees, 2 very crucial aspects of your course.Measuring angles is much like measuring distances or mass, you can use different units. So much like you could measure a box with cm or inches, you can measure angles in degrees or radians. The crucial thing to remember is that there are 2 pi radians in a full circle, therefore pi radians is the same as 180 degrees, or pi/3 radians is the same as 60 degrees. Don't stress about trying to memorise all of the conversions, the exams like to ask about the same common angles (pi/6 = 30 degrees, pi/4 = 45 degrees, pi/2 = 90 degrees, 2pi/3 = 120 degrees) so by doing practise questions invloving radians you'll get accustomed to these without even thinking about it;)