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Envision Math 2.0: Grade 8, Volume 2

EM

Envision Math 2.0: Grade 8, Volume 2 View details

Review

Exercise 2 Page 448

The surface area of a sphere is four times the product of π and the square of the radius.

100πcm^2

Practice makes perfect

We will find the surface area of the given sphere.

The surface area of a sphere is four times the product of π and the square of the radius. S.A.=4π r^2 In the diagram we can see that the diameter is 10cm. Therefore, the radius is 10÷ 2= 5cm. We can substitute this value for r in the above formula and simplify the right-hand side.

S.A.=4π r^2

r= 5

S.A.=4π ( 5)^2

▼

Simplify right-hand side

Calculate power

S.A.=4π (25)

CommutativePropMult

Commutative Property of Multiplication

S.A.=4(25)π

Multiply

S.A.=100π

The surface area of the given sphere, in terms of π, is equal to 100π square centimeters.

Subchapter links

Topic Essential Question p.447

Vocabulary Review p.447

Use Vocabulary in Writing p.447

1 Find Surface Area of Three-Dimensional Figures p.448

2 Find Volume of Cylinders p.449

3 Find Volume of Cones p.449

4 Find Volume of Spheres p.450