Question

A subtending arc on a circle with a radius of 4.5 centimeters has an arc length of 8π. The measure of the angle subtended by the arc is what?

Answer 1

For the answer to the question above, 

the angle of 360 ° → π.d 

the angle of x ° → 8π 


You make the cross-multiply and you can get: 

x * π.d = 8π * 360 

x * d = 8 * 360 

x = 8 * 360/d → where d = 2r 

x = 8 * 360/2r 

x = 4 * 360/r → where r = 4.5 cm 

x = 4 * 360/4.5 

x = 320 °