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2 π r = circumference. The circumference of a plate is 31”. Find the diameter. Radius of plate is 5”. 2 πr = 31. 2 πr = 31. Find the diameter. 2 π = 2 π. 6.28 r = 31. Diameter of plate is 10”. 6.28 = 6.28. 2 π r = circumference. The circumference of bottom of cupcake
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2πr = circumference The circumference of a plateis 31” Find the diameter
Radius of plate is 5” 2πr = 31 2πr = 31 Find the diameter 2π = 2π 6.28r = 31 Diameter of plate is 10” 6.28 = 6.28
2πr = circumference The circumference of bottom of cupcake Is 6.5” Find the diameter
Radius of cupcake is 1” 2πr = 6.5 2πr = 6.5 Find the diameter 2π = 2π Diameter of cupcake is 2” 6.28r = 6.5 6.28 = 6.28
2πr = circumference The circumference of top of a mug is 13” Find the diameter
r = 2” 2πr = 13 2πr = 13 Find the diameter 2π = 2π d = 4” 6.28r = 13 6.28 = 6.28
r = 50cm The circumference of wheel is 314 cm 2πr = 314 2πr = 314 Find the diameter 2πr = circumference 2π = 2π d = 100cm 6.28r = 314 6.28 = 6.28
r = 16cm 2πr = 100 The circumference of the top of a water pail is 100 cm 2πr = 100 2πr = circumference Find the diameter 2π = 2π 2πr = 100 d = 32cm 6.28 = 6.28
r = 3965 The circumference of the earth is 24,901 miles 2πr = 24,901 2πr = 24,901 Find the diameter d = 7930 2π = 2π 2πr = circumference 2πr = 24,901 6.28 = 6.28
A circle with radius 3 cm is enlarged so its radius is now 6 cm Draw a figure to represent this idea
By what scale factor did the circumference increase? 2π(6) = c 2π(3) = c 6.28(6) = c 6.28(3) = c c = 38 c = 19
By what scale factor did the area increase? π(6)(6) = a π(3)(3) = a 4 3.14(36) = a 3.14(9) = a 113cm = a 28cm = a