PLZ HELP ASAP AREA OF A SECTOR

The area of a sector is computed by below formula

Asector = 0.5*r^2*∅

where r is the radius and ∅ = angle measured in radians. 

In the picture r = 4 units and ∅ = 8/5(π)
Using the formula. 

A = 0.5 (4^2)(8/5*π)
A = (12.5)π or 40.122386 units