Formulas for Common Geometric Shapes
Depending on the algebra problem, you'll need to know some geometry. The following represents some of the most common shapes in geometry and their formulas for perimeter, area, volume, surface areas, and circumference:
Two-Dimensional Shapes
| Shape | Perimeter/Circumference | Area |
| Rectangle |
P = 2(l + w) |
A = lw |
| Square |
P = 4s |
A = s2 |
| Triangle |
P = a + b + c |
A = 1/2bh |
| Trapezoid |
P = a + b1 + c + b2 |
A = 1/2h(b1 + b2) |
| Isosceles Trapezoid |
P = 2w + b1 + b2 |
A = 1/2h(b1 + b2) |
| Circle |
C = πd = 2 π r |
A = π r2 |
Three-Dimensional Shapes
| Shape | Surface Area | Volume |
| Box |
SA = 2lw + 2lh + 2wh |
V = lwh |
| Sphere |
SA = 4 π r2 |
V = π r3 |
| Cylinder |
SA = 2 π r(r + h) |
V = π r2h |
