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The area of the entire surface of a truncated cone with the radius of the lower base R = 1, with the radius of the upper base r = 3, and the generative L = 4 equal to 81.679

What needs to be found:
Radius R: Radius r: Forming L:

truncated cone

A truncated cone is a part of a cone located between its base and a secant plane parallel to the base.
The formula for the area of the entire surface of the cone Formula for the area of the entire surface of a truncated cone truncated cone where R is the radius of the lower base,r is the radius of the upper base, L is the length of the generatrix.

Solution:
S = π·(R2+(R+r)L+r2)
= π·(12+(1+3)4+32)
= π·(1+4·4+9)
= π·(1+16+9)
= 26·π
=
81.679

a: The area of the entire surface of a truncated cone with the radius of the lower base R = 1, with the radius of the upper base r = 3, and the generative L = 4 equal to 81.679