To do this you would first find the area of the square which is 16. Then you would find the area of the 2 semicircle or just on whole circle. We are just going to use the formula for a whole circle since there are 2 semicircles. The formula to find a circle is pi times r^2 so we are going to put that into a calculator so we would do pi times 2 (radius of circle)^2 which is 12.57 and we would subtract 16 by 12.57 which is 3.43
Students might also scale up using part-to-whole-ratios and come up with 35 parts total and 14 parts red for Plan A and 35 parts total and 7 parts red for Plan B.
