Hello,

the shaded area can be calculated by:

area of sector - area of right triangle

The angle(ROP) =

Thus the area of the sector is:

The area of the right triangle is

If r is the length of the radius (here r = 4 cm) then the length of the base: and

the length of the height is:

Therefore the shaded area is:

Plug in the values you know to calculate the area.

(For confirmation only: I've got A = 1.017 cm²)