How To Find Surface Area?

Identify the shape and its dimensions

Determine which faces make up the surface

Find the area of each face (use the correct formula for each face)

Add all face areas together to get total surface area

Common formulas

Rectangle: (A=lw)

Square: (A=s^2)

Triangle: (A=tfrac12 bh)

Circle: (A=pi r^2)

Parallelogram: (A=bh)

Trapezoid: (A=tfrac12 (b_1+b_2)h)

Regular polygon (perimeter method): (A=tfrac12 aP) where (a) is apothem and (P) is perimeter

Surface area of prisms

Total surface area: (SA=2B+Ph)

(B) = area of base, (P) = perimeter of base, (h) = height

Surface area of cylinders

Total surface area: (SA=2pi r^2+2pi rh)

Lateral area only: (LA=2pi rh)

Surface area of pyramids

Total surface area: (SA=B+tfrac12 Pl)

(B) = base area, (P) = base perimeter, (l) = slant height

Surface area of cones

Total surface area: (SA=pi r^2+pi rl)

Lateral area only: (LA=pi rl)

Surface area of spheres

Total surface area: (SA=4pi r^2)

Lateral area only (when needed)

Prism: (LA=Ph)

Pyramid: (LA=tfrac12 Pl)

Cylinder: (LA=2pi rh)

Cone: (LA=pi rl)

Sphere: no separate lateral area (full surface)

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