Find the Angle,in Radians,in the Figure Below If S = $\frac { 13 \pi } { 5 }$

Multiple Choice

Find the angle,in radians,in the figure below if S = 13 and r = 5.

A) $\frac { 13 \pi } { 5 }$
B) $\frac { 5 } { 13 }$
C) $\frac { 13 } { 5 }$
D) $\frac { 5 \pi } { 13 }$
E) $\frac { 18 \pi } { 5 }$