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.
