三角形
S = a * h / 2
圆形,球
C = 2 * π * r
S = π * r ^ 2
V = 4 / 3 * π * r ^ 3
矩形,长方体
C = 2 * a * b
S = a * b
V = a * b * h
正方形,立方体
C = 4 * a
S = a ^ 2
V = a ^ 3