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Calculating the Surface Area
of Triangular Prisms, Pyramids
& Cylinders
• To work out the surface area of a 3D shape, draw its net.
• Surface area of a cylinder equals 2πr(r + h). When the height is
a multiple of the radius, surface area equals xπr², where x is the
coefficient incremented by 1 then doubled (height three times
radius = 3r = 3 + 1 = 4 × 2 = 8. SA = 8πr²).
• To find out how many shapes can be cut out from a given
area, you divide the corresponding values (circumference
to length, width to width, etc.), and then multiply your two
quotients.