Question

Why is pi = 180 degrees radians?

Answer 1

Think of a circle.
Now think of half of it and focus on the crust or contour of it: What is its length? Well if an entire circle is `2pi*r` half will be only `pi*r` but half a circle corresponds to `180°` ok...Perfect....

and here the difficult bit:
radians is: (arc length)/(radius)
Your arc length, for half circle, we saw that was `pi*r` dividing by `r`...you get `pi` radians!!!!!!

Is it clear?...probably not...