Question

a circular photo frame has an outer radius 20cm and inner radius 18cm.find the width of the frame around the photo.also the cost of painting it with metallic colour at the rate of $0.7 per cm square.take 22÷7

Answer 1

width of the frame = outer radius- inner radius
                              = 20 - 18 = 2cm

area of frame = $\pi$$(R ^{2}$-$r^{2}$)

= 22/7 x (400-324)

= 22/7 x 76

= 22 x 185/100

= 40.7

Cost = area x rate

= 40.7 x 0.7

= $28.49

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