first, you want to find the area of the whole circle. the formula for the area of a circle is pi r squared where r = radius
so we need radius squared x pi (3.14)
the radius of the big circle is 8. 8 squared is 64. 64 times 3.14 is 200.96
so the area of our big circle is 200.96
then, we need to subtract the area of the smaller circle. we know that the width of the shaded part is 3cm. the width of the bigger circle is 8cm (also the radius). so the radius of the smaller circle is 8-3, which is 5
now we can use the circle formula to find the area of the smaller circle (pi r squared)
5 squared is 25. 25 x 3.14 is 78.5.
now we subtract the area of the smaller circle. 200.96 minus 78.5 is 122.46.
