The geometry and graphics of the sixth grade are the area of the circle and the related shadows.

Sub-fields include

1, outer and inner circle, find the area of the shadow part, and use the square area.

Reduce the area of the circle. The area of the circle is the square of the radius.

The area of a shape is the side length multiplied by the side length, which is four times the square of the radius, so

Equal to the square of radius 0.86x

2. In the outer circle, find the area of the shadow part and subtract it from the area of the circle.

The area of a circle is the square of the radius, square.

The area of the shape is twice the square of the radius, so it is equal to 1. 14x radius.

square