Page 60 - Math Course 3 (Book 2)

Surface Area of Pyramids and Cones

Then find the surface area. The base of the Surface Area of a Cone
pyramid is a square.

S = L + B Write the formula. Example

= L + s² The area of a square is s². Find the surface area of the cone. Round to the

= 142.4 + 8² Substitution. nearest tenth.

= 206.4 ft² Simplify. 10 ft

Is your answer reasonable? 3.5 ft

The surface area of the square
Answer
pyramid is 206.4 square feet.

S = πrℓ + πr² Formula for surface area
of a cone
Real World Example
= π(3.5)(10) + π(3.5)² Replace r with 3.5 and
ℓ with 10.
CANOPIES
A canopy is in the shape of a square pyramid that ≈ 148.4 Simplify.
is 3.4 meters on each side. The slant height is 2
meters. How much canvas is used for the canopy? Answer The surface area of the cone is
about 148.4 square feet.
Find the lateral area
only, since there is
no bottom to the
canopy. Your Turn!

Surface Area of a Pyramid
Find the surface area of the square pyramid.

A. 16.5 m²
1
Estimate L = 4( )(3)(2) = 12 B. 33 m²
2 C. 42 m² 5.5 m
D. 75 m²
1
L = 4( )bh Formula for area of 4 triangles
2
1
= 4( )(3.4)(2) Replace b with 3.4 and h with 2.
2
= 13.6 Simplify.

3 m
13.6 square meters of canvas
was used to cover the canopy.
Answer
Compare your answer to the Answer
estimate.

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