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McGraw Hill Glencoe Geometry, 2012

MH

McGraw Hill Glencoe Geometry, 2012 View details

1. Circles and Circumference

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Exercise 56 Page 705

Use the formula for circumference of a circle and solve it for the radius.

A

Practice makes perfect

We want to find the radius of the circle formed by a table. The circumference

C

of a circle with radius

r

is calculated using the formula below.

C = 2 π r

From the exercise, we know that the circumference of the circle is

10 ft .

By substituting

10

for

C

in the formula, we can solve for

r .

C = 2 π r

$C = 10$

10 = 2 π r

Multiply

10 = 2 π r

$LHS / 2 π = RHS / 2 π$

\frac{1 0}{2 π} = r

Rearrange equation

r = \frac{1 0}{2 π}

Use a calculator

r = 1.591549 \dots

Round to $1$ decimal place(s)

r \approx 1.6

The radius of the circle is approximately

1.6 ft .

Therefore, the correct answer is A.

Subchapter links

Check Your Understanding p.701

Practice and Problem Solving p.701-704

H.O.T. Problems p.704

Standardized Test Practice p.705

Spiral Review p.705

Skills Review p.705