The circle area formula is A=pi r^2. I am assuming those numbers represent diameter, and diameter is radius x 2. 6/2=3, and pi 3^2= 28.27433388. Divide this by 2 and the area of your half circle is 14.13716694. On the other half circle, 5/2= 2.5. pi times 2.5^2 is 19.63495408, divided by two is 9.817477042. Hope it helps!