SPI I CAN identify parts of a circle. I CAN find the circumference and area of a circle.

Circle – named from the center point. Radius – one endpoint at the center; the other endpoint on the circle Diameter – a segment that passes through the center and has both endpoints on the circle

Chords – endpoints on the circle Central angle – an angle with its vertex at the center.

Diameter equals 2 radius OR Radius is half the diameter D = 2rORR= d/2 Example: r = 5 in; d = ? D = 140 in; r = ? radius diameter

Pi = 3.14 = = The ratio C = a number close to 3. d C = ∏d OR C = 2∏r the distance around a circle

A = ∏ r ² OR A = ∏ x r x r Ex. r = 5 cm 5 cm amount of surface covered

 Find the circumference. 1)d = 50 m 2)r = 64 m  Find the area. 3)11 in 4)16 cm

Radius 0.8 cm Round to the nearest whole number. C = 5 cm A = 2 cm²

Diameter 1.5 cm Round to the nearest tenth. C = 4.7 cm A = 1.8 cm²

518.1 ft

ft

A in

C in

If the r = 7m, then d = _____, C = _____, and A = ______. d = 14m C = 44m A = 154m²

If the d = 11.5 ft, then r = _____, C = _____, and A = ______. r = 5.75ft C = 36ft A = 104ft²

Circumference 1.57 in Diameter ? d = 0.5 in