The semicircle below has a diameter of 20, find the area of the blue region
You can minus the area of the triangle from the area of the semi-circle, and that'll give you the answer
To be more specific...
Formula for area of a semicircle: A=pi*r^2/2
Formula for area of a triangle: A=B*H/2
Also...
The same question was posted here as well: https://web2.0calc.com/questions/help-me-asap-please_2#r2