Warm up for Section 4.8.

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Presentation transcript:

Warm up for Section 4.8

Answers to Warm up for Section 4.8 C ≈ 50.27 ft 65.98 = 2r 65.98/(2) = r 10.50 cm ≈ r Length AB = 150 360 ≈ 47.12 in. ∙ 2(18)

1. 2. 3. 4. 5. 6. 7. 8. 114.02° 9. 58.03 in. 10. 20.53 cm 11. 30 + 5π ≈ 45.71 mm 4.7 Homework Answers

Area of a Circle and a Sector Section 4.8 Standard: MM2G3 cd Essential Question: How do I find the area of a sector using the measure of a central angle?

Before beginning this section, you must remember a few formulas that you have learned in the past: The area of a circle is given by the formula:

A sector is the region bounded by two radii of the circle and their intercepted arc. It is a portion of the entire area.

A is the center of the circle at right. 6 40˚ What is the total area of the circle? We will use this information to find the area of the shaded sector. The formula for the area of a sector is very similar to the formula for arc length.

The formula for the area of a sector is given by: Using the formula above, we can determine the area of the shaded sector. A 6 40˚

Find the area of circle Y. Area of circle = A X Area of shaded Sector = 95 cm2 Y 150˚ Z The area of the circle is 228 cm2.

Find the area of both sectors. Area of circle = 21 mm Area small sector: 110˚ B C Area large sector:

The small sector has area 423.33 mm2 and the 110˚ B C The small sector has area 423.33 mm2 and the large sector has area 962.11 mm2.

Find the area of circle H. Area of circle = A F 70˚ G H Area of shaded region is 123.45 m2 The area of circle H is 634.89 m2.