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McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

2. Surface Areas of Prisms and Cylinders

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Exercise 25 Page 819

Use the formula for the lateral area of a cylinder.

r = 9.2 cm

Practice makes perfect

We are asked to find the radius of the given cylinder.

Let's recall the formula for the lateral area L of a cylinder. L=2π rh Here, r is the radius of the base, and h is the height of the cylinder. Since we are given that the height is 11 cm and the lateral area is 653.9 cm^2, we can substitute them into the formula and calculate the length of the radius.

L=2 π r h

L= 635.9, h= 11

635.9 = 2 π r( 11)

▼

Evaluate right-hand side

Multiply

635.9= 22 (π)(r)

.LHS /22π.=.RHS /22π.

635.9/22π=r

Use a calculator

9.200602 ... = r

Rearrange equation

r ≈ 9.200602 ...

Round to 1 decimal place(s)

r ≈ 9.2

The radius of the prism is 9.2 cm.

Subchapter links

Exercises p.817-821