Presentation is loading. Please wait.

# Using Radius to Find Circumference

## Presentation on theme: "Using Radius to Find Circumference"— Presentation transcript:

Using Radius to Find Circumference
EXAMPLE 1 Using Radius to Find Circumference Find the circumference of a circle with a radius of 11 meters. SOLUTION C = 2πr Circumference formula 2(3.14)(11) Substitute 3.14 for π and 11 for r. = 69.08 Multiply. ANSWER The circumference is about meters.

. 213 EXAMPLE 2 Using Diameter to Find Circumference
Find the circumference of the circle. SOLUTION The measure shown is a diameter, so use the circumference formula that involves the diameter. C = πd Circumference formula 22 71 . 213 Substitute. Use for π because 21 is divisible by 7. 22 7 = 66 Multiply ANSWER The circumference is about 66 feet.

Standardized Test Practice
EXAMPLE 3 Standardized Test Practice SOLUTION You are asked to find the diameter, so use the circumference formula that involves diameter. C = πd Circumference formula d Substitute for C and 3.14 for π. = 3.14d Divide each side by 3.14. 135 = d Simplify. ANSWER The diameter is about 135 feet. The correct answer is C.

Use for π because 28 is divisible by 7. ANSWER
GUIDED PRACTICE for Examples 1, 2, and 3 Find the circumference of the circle. Use 3.14 or for π . Explain your choice of π . 22 7 1. Use for π because 28 is divisible by 7. ANSWER The circumference is about 176 mi.

GUIDED PRACTICE for Examples 1, 2, and 3 Find the circumference of the circle. Use 3.14 or for π . Explain your choice of π . 22 7 2. Use 3.14 for π because 9.5 is not divisible by 7. ANSWER The circumference is about m.

GUIDED PRACTICE for Examples 1, 2, and 3 Find the circumference of the circle. Use 3.14 or for π . Explain your choice of π . 22 7 3. Use 3.14 for π because 16 is not divisible by 7. ANSWER The circumference is about cm.

GUIDED PRACTICE for Examples 1, 2, and 3 4. diameter = 32 in. Use 3.14 for π because 32 is not divisible by 7. ANSWER The circumference is about cm.

The circumference is about 440 ft.
GUIDED PRACTICE for Examples 1, 2, and 3 5. diameter = 140 ft. ANSWER The circumference is about 440 ft. Use for π because 140 is divisible by 7. 22 7

GUIDED PRACTICE for Examples 1, 2, and 3 6. radius = 1.5 km Use 3.14 for π because 1.5 is not divisible by 7. ANSWER The circumference is about 9.42 cm.

GUIDED PRACTICE for Examples 1, 2, and 3 7. What If? In Example 3, suppose the circumference of the Ferris wheel is 462 feet. What is the diameter of the Ferris wheel? ANSWER The diameter is about 147 feet.

Download ppt "Using Radius to Find Circumference"

Similar presentations

Ads by Google