## How is the formula for surface area of a cone derived?

The total surface area of a cone is the combination of the curved surface as well as the base area of a cone. The formula to calculate the total surface area of the cone is: TSA of cone = πr2 + πrl = πr(l+r) square units.

**How do you find the development of a cone?**

To calculate the dimensions of the development, first the slant height of the cone must be found from Pythagoras’ theorem, ie R = √ [ H^2 + ( D/2 )^2]. The sector angle θ is found from the formula θ = D x ( 180 / R ), which gives θ in degrees. Draw the arc with compasses set to a radius of R .

**What is the formula for finding the angle in the development of cone?**

Angle = (D1 x 360) / D2 Where: Angle = the included angle between the outside lines of the main development. D1 = the diameter is of the base of the cone (see diagram below) D2 = the diameter is of the developed cone, which you get from the elevation of your cone (see diagram below)

### What are different methods of development of surfaces?

Parallel-line development: Used for prisms, cylinders etc. in which parallel lines are drawn along the surface and transferred to the development. Radial-line development: Used for pyramids, cones etc. in which the true length of the slant edge or generator is used as radius.

**Why is the volume of a cone calculated?**

The formula for the volume of a cone is one-third of the volume of a cylinder. The volume of a cylinder is given as the product of base area to height. Hence, the formula for the volume of a cone is given as V = (1/3)πr2h, where, “h” is the height of the cone, and “r” is the radius of the base.

**What is the formula of surface area of rectangle?**

You can use the following formula to find the area of a rectangle. Step 1: Multiply the length by the width. Step 2: L X W , where L is the length and W is the width. A square which is also a type of rectangle with all equal sides.