If the length of AB is 20cm.
What is the area between the two circles?
Label the centre of the circle , the midpoint ofOriginally Posted by Natasha1
the radius of the smaller circle and the radius of the outer circle .
Then triangle is a right triangle with hypotenuse
and the other sides , and . Therefore by Pythagoras:
,
or:
The area of the annulus is:
RonL