Question

The inner and outer Radii of a cylindrical pipe are 5 cm and 4 cm respectively. find the area of cross section of the pipe. 

Answer 1

28.3 cm²

Explanation:

You find the area of the whole section which is 5²π = 25π.

Then you find the area of the empty part which is 4²π = 16π.

Then you subtract to get 9π which is 28.27433388......

= 28.3 cm²

Answer 2

To do this find the area of the inner pipe, and then find the area of the outer pipe, then subtract the larger of the two from the smaller, and that is the area of the cross section