AREA OF CIRCLES AND SECTORS. Area of a circle The area of a circle is π times the square of the radius, or A= πr 2.

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Areas of Circles and Sectors

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Presentation transcript:

AREA OF CIRCLES AND SECTORS

Area of a circle The area of a circle is π times the square of the radius, or A= πr 2

Examples Find the area of a circle with radius 8 inches. A=πr 2 =π*8 2 = π*64 = ( approximately) Also, when we have a diameter we need only take half of the diameter since d=1/2r.

Area of a Sector The ratio of the area A of a sector of a circle to the area of the circle is equal to the ratio of the measure of the intercepted arc to 360 degrees.

Examples Find the area of the sector such the sector cpd intercepts an arc whose measure is 80 degees. The radius is 4 ft. **Work on your own for 2 minutes***

Using Areas of Circles and Regions To determine the area of a shaded region inside a circle, you will need to follow this formula: Area of Shaded Region=Area of a circle-Area of non-shaded region.

Homework: Complete the handout and bring it back before next class for credit.