What is a Cone?
We can define a cone as a 3-dimensional solid object that has a circular base joined to a point by a curved side. The point is known as a vertex.
There are two types of cones;
- A right cone is one whose apex is perpendicular to the base , which means that the perpendicular line falls exactly on the center of the circular base of the cone
- An oblique cone. If the position of the vertex is anywhere apart from the center of the base, then it is an oblique cone.
Properties of a Cone.
- It has one circular face.
- It has zero edges.
- It has one vertex.
Cones can be found in a variety of things we see everyday. Some examples are as follows:
- A funnel is shaped like a cone.
- An ice cream is scooped in a conical pastry.
- The barriers we see on roads are also conical.
- The birthday hats are conical in shape.
Formula to Calculate Surface Area of a Cone.
The formula to find the total surface area of a cone, is the sum of the area of the circle which is its base and the area of the lateral surface also known as its side.
Whereby; r is the radius of the cone.
l is he slant height of the cone.
h is the perpendicular height of the cone.
Example:
Calculate the surface area of a cone whose slant height is 10 cm, its perpendicular height is 5 cm and its radius is 4 cm.
Therefore, the surface area of the cone is 175.952 cm².
