Arc area formula How to calculate the area of Arc? (in the case of chord height, chord length and height)

Arc area formula How to calculate the area of Arc? (in the case of chord height, chord length and height)

This can be derived
The circumference of a circle is the product of the diameter and the circumference, and the corresponding center angle is 360 degrees;
The arc length of an arc is: the quotient of the center angle of the arc and 360 degrees, and then the product of the circumference of the circle
If the diameter D, the center angle α corresponding to the arc and the circumference π, the arc length formula is as follows:
l=πDα÷360