You need to find the radius of the circle.
You are told that the curved part is a semicircle.
That means that the endpoints of the curved part are the endpoints of a diameter.
Find the length of the diameter by using the Pythagoras theorem.
Then divide by 2 to get the radius.
Then find the area of the circle and divide by 2 to find the area of the semicircle.
Then find the area of the triangle.
Add the areas of the semicircle and triangle..
