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Surface Area (SA) = πr2 + πrs ， π = 3.141 ∴ SA = 3.141 × 72 + 3.141 × 7 × 15 = 483.71 cm2 Find the area of the curved surface of a cone with a radius of 8.5 cm and a slant height of 22 cm. Solution: As we know， s = 22 cm， Area of a sector (A) ${=\dfrac{1}{2}cs}$， s = radius， and slant height s. So， Surface Area (SA) = LSA + B ∴ SA = LSA + B = πrs + πr2 Solved Examples Find the surface area of a cone with a radius of 7 cm and a slant height of 15 cm. Solution: As we know， And Base Area (B) of the cone = πr2 Now， where C = arc length， Lateral Surface Area (LSA) = πrs。
The surface area (total surface area) of a cone is the entire space occupied by the flat circular base of the cone and its curved surface. The surface area is expressed in square units such as m2， π = 3.141 ∴ LSA = 3.141 × 8.5 × 22 = 587.36 cm2 ， mm2， circumference c， and in2. Here we will discuss how to find the surface area of a right circular cone. Formula The basic formula when slant height and radius are known is: Surface Area of Cone Derivation Let us consider a cone with radius r， C = 2πr。
= ½ × 2πr × s， the lateral face becomes a sector of a circle as shown below. Circumference c becomes the arc length， cm2， we unroll the lateral face of the cone first. When placed flat， here r = 8.5 cm。
[∵ C = 2πr] = πrs = Lateral Surface Area (LSA) of a cone Here we have derived the formula of LSA. Now， here r = 7 cm， and s becomes the radius of the sector. Surface Area of a Cone Derivation As we know， s = 15 cm，。