To do so, we must know that the lateral area of a right cone is half the product of the circumference of the base and the slant height.
L.A.=1/2* 2π r* l ⇔ L.A.=π rl
In this formula, r is the radius and l is the slant height of the cone. Since we know that the diameter d is equal to 7, we can divide it by 2 and get the radius of the base.
r=7/2 ⇒ r= 3.5
With this information we are able to calculate the lateral area of the cone. To do so, we will substitute r= 3.5 and l= 21 into the formula for the lateral area. Let's do it!
