To find the area of the shaded region you divide the figure into:
2 semicircles and one triangle, as fllow:
First semicircle and triangle:
Second semicircle:
The area of the shaded area is the sum of Area 1 and 2 (semicircle and triangle) less the area of semicircle 3.
Area 1:
The area of a semicircle is:
The semicirlce 1 has a diameter of (4cm+4cm+8cm=16cm) the radius is the half of the diameter (8cm):
Area 2:
The area of a triangle is:
The given triangle has height of 3cm and a base of 8cm:
Area 3:
The semicirlce has a diameter of 8cm, the radios os the hal od the diameter (4cm):
Then, the area of the shaded region is approximately: 87.40 squared centimeters