oh Math whizzes!
The boy is trying to make parachutes for his science project. One is a pyramid, one is round, and one is an octagon. To be similar, he wants to make them have a similar surface area.
We want to figure out the octagon area. Do we have enough factors? So we broke it down into the surface area of the 8 triangles in the octagon. As though it was a flat sheet of paper. If the original diameter of the circle (before cutting the edge off) is 50 cm, then each of the two sides is 25 cm (a radius, right?). The angles will always be 67.5, 67.5 and 45 (right?).
So what is the formula?
What size is the base of these triangles?
What size is the height of these triangles?
Is the area of each of the triangles then multiplied by 8 to get the surface area?