Solve for angle alpha and angle theta by Cosine Law. With angle alpha known you can find angle beta.

The shaded area is equal to a circular sector of radius 7 cm with central angle beta minus circular segment with of radius 14 cm with central angle 2-theta minus isosceles triangle of equal sides 7 cm with included angle beta.

Please guys help me

Solve for angle alpha and angle theta by Cosine Law. With angle alpha known you can find angle beta.

The shaded area is equal to a circular sector of radius 7 cm with central angle beta minus circular segment with of radius 14 cm with central angle 2-theta minus isosceles triangle of equal sides 7 cm with included angle beta.