To start with we have to write down what we know. pi=3.14, r=9, arc length is 1. x is the angle we are trying to find. Saying that the radius is 9
There is an equation that states that the arc length is equal to x/360 (the fraction of the circle) multiplied by the circumference or 2 times pi times the radius.

where * means multiply.

Simplify

Take the 28.26 over to the other side of the equation, where it then it divides the 1.

This becomes:

Then the 360 is brought over to the other side and multiplies the 0.035:

And finally simplify the whole equation and we get our answer.
