$\"\"$

Diameter of thr canvas is $\"\"$ .

Radius of the canvas is $\"\"$ .

Removing a sector with central angle is $\"\"$ .

The angle of sector is $\"\"$ .

Area of the sector is $\"\"$ , where $\"\"$ is in radians.

$\"\"$ .

Substitute $\"\"$ and $\"\"$ in $\"\"$ .

$\"\"$

$\"\"$ .

Area of the sector is $\"\"$ .

$\"\"$

Area of the sector is $\"\"$ .