Make: Geometry

9-15 shows the net laid flat, and Figure 9-16 shows it folded up into the prism.

To try this out, 3D print a prism with a square base using the

pyramid_prism_net.scad model. Based on the values of r and h you

input, estimate the surface area. Then try measuring the produced model

and seeing how close you got. Remember that the radius of the base (r)

parameter isn’t a side of the base. The radius is the distance from a vertex of

the base to the center. If we have a square base, the radius is the hypotenuse

of a right triangle s/2 on each side. The Pythagorean theorem tells us that

r

2

=(s/2)

2

+ (s/2)

2

which we can simplify to

r

2

=2s

2

/4

or fur ...