Summary

To calculate the surface area of a cone, you can use the PI function together with the exponent operator (^) and the SQRT function. In the example shown, the formula in D5, copied down, is:

=1/3*PI()*B5^2*C5

The formula returns the surface area of a cone with radius given in column B and height given in column C. Units are indicated generically with "u", and the resulting area is units squared (u2).

Generic formula

=PI()*r*(r+SQRT(h^2+r^2))

Explanation 

In geometry, the formula for calculating the surface area of a right cone is: 

The Greek letter π ("pi") represents the ratio of the circumference of a circle to its diameter. In Excel, π is represented in a formula with the PI function, which returns the number 3.14159265358979, accurate to 15 digits:

=PI() // returns 3.14159265358979

To square a number in Excel, you can use the exponentiation operator (^):

=A1^2

To get the square root of a number, you can use the SQRT function:

=SQRT(A1)

Rewriting the formula for surface area of a cone with Excel's math operators, we get:

=PI()*B5*(B5+SQRT(C5^2+B5^2))

Following Excel's order of operations, exponentiation will occur before multiplication.

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.

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