## Elementary Geometry for College Students (7th Edition) Clone

Given the length of the arc is 4$\pi$ in which is 90$^{\circ}$ arc We need to find out the length of the radius of the circle In a circle whose circumference is c, the length l of an arc whose degree measure is m is given by l =$\frac{m}{360}$ * c where c = 2$\pi$ r , m= 90$^{\circ}$ l= 4$\pi$ in. Therefore 4$\pi$ = $\frac{90}{360}$ * 2$\pi$ r r = 4*2 = 8 in. The radius of the circle = 8 in