Question

What is the arc length of the subtending arc for an angle of 72 degrees on a circle of radius 4?

Answer 1

We know that

[the length of a circumference]=2*pi*r
for r= 4 units
[the length of a circumference]=2*pi*4--------------> 25.12 units

if a  full circle (360°) has a length---------------------> 25.12 units
 arc for an angle of 72 °---------------------------> X
X=72*25.12/360------------> 5.024 units

the answer is 
the length of the subtending arc for an angle of 72° is 5.024 units