I was sitting the other day with my cousin, helping him with his homework, when he asked me what's the deal with these radians.
So I took a paper and a pen and tried to recall where did these radians come from, but something is not quite clear for me.
Consider the following circle:
When the angle is 90 degrees, arc a is exactly the length of the full circle's perimeter.
and therfor the angle in radians is:
So when r=1, we're good, we get:
But obviously, it is not the case for any other r, as it should be...
So what am I missing here?
Thanks in advanced!