I'm either misinterpreting the problem, or it's incorrect. First of all, I'm asuming that the picture is supposed to be part of a circle. Thereofre we know that x, the measure of the angle in radians, multiplied by r, the radius, has to be 10. Now, you're saying that theta * r also equals 10, therefore theta must equal x. That means that x*(180/pi) = x. That means 180/pi = 0, which is incorrect. Am I wrong somewhere?