Its area is pr 2. The mathematical principle is to slice small discs shaded in yellow of thickness delta y and radius x. Our area formula is now.
Taking the square root graphs as only half a cone.
Where r is the base radius of the cone. Its area is pr 2. A p r 2 A side The Area of the Side. To do so he had to use a formula for the volume of a cone which we derive in video II.