- #1

Mantaray

- 17

- 0

## Homework Statement

I tried to calculate the area of a sphere using the function [tex]f(x) = \sqrt{1-x^2}[/tex]

## Homework Equations

hmm?

## The Attempt at a Solution

So I thought I could slice up the sphere in small cylinders, and then calculate the outer surface by circumference * height of all the cylinders and then add them together.

In this case, the radius would be equal to f(x) and the height of the cylinder would equal [tex]\Delta x[/tex]. So the surface of the whole sphere would be:

2pi \int f(x) dx with lower limit -1 and upper limit 1. However, this does not seem to equal 4pi*r^2, I checked this with r = 1. It gives two quite distinct values.

Where did I go wrong?