Question

Find the circumference of the circle whose area is 16 times the area of the circle with diameter 7 cm

Answer 1

r of circle whose d is 7cm = 7/2 cm. 
Area of circle = 7×7×22÷7×2×2 = 77/2 cm^2. 
Area of 2nd circle = 77×16÷2 = 616 cm^2. 
pi R^2 = 616 cm^2
R^2 = 616 ×7÷22 = 28×7 = 196 
R = 14 cm
Circumference = 2 pi R = 2×14×22÷7 = 88cm

Answer 2

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