The thing that is most important is that the horizontal line connect h and the radius is parallel to the cut of the sphere if it was placed right in the middle. That line swings around as though the center was a pivot.
Solution
So what you have is a circle when that line goes around that part of the sphere.
To find the length of that line, use the Pythagorean Theorem. Call the line r1.
F(g(x)) means you take the g function and put it into x in the f function. He took the function and put it into the g, which was the incorrect order. He should have had this:
Well I'm not sure what the answer would be since I'm not that smart but I did get the answer of 90, I did this by dividing 72 by 80 which equals .9 and I multiplied that by 100 and got 90.
