hi zee-f

Oh dear. A bit of a muddle. You had the correct yellow area back in post 81.

Also remember in post 79 you had a good estimate of the answer by counting squares. I said then, I thought it was a bit high. So you should not be satisfied untill you land up with an answer that is somewhere between these two.

Let me set out for you what you should be calculating.

step 1. area of yellow quadrants = 3/4 x 50^2 x PI =

step 2. area of red quadrant = 1/4 x 30^2 x PI =

step 3. area of green quadrant = same answer =

step 4 estimated area (overlap) = 95

step 5. add up 1, 2 and 3 and take away 4 total =

Please set it out like this then, if there is still a gremlin lurking in there, I can see where it is.

Bob

Bob