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Question

Alice80

P6 Mathematics

Question post on Thu, 19/04/2018 8:14pm

Please help. Can we have exact answer without rounding to nearest decimal places?

Answer

alfretztay · Answer 1 · Post on Thu, 19/04/2018 9:02pm

288/2 = 144 (area of 1/2 square) = (1/2) x 2r x r = r^2
r = sq rt 144 = 12
area of blgger/outer circle = 3.14 x 12 x 12 = 452.16
area of shaded part = 452.16 – 288 = 164.16

Ans : 164.16 sq cm.

Alice80 · Answer 2 · Post on Thu, 19/04/2018 10:18pm

Alice80 Post on Thu, 19/04/2018 10:18pm

Hi, may I know why r = sq rt 144 = 12?

alfretztay · Answer 3 · Post on Thu, 19/04/2018 11:03pm

288/2 = 144 (area of 1/2 square) = (1/2) x 2r x r = r^2 (Note : A triangle, area of which is (1/2) x base, 2r x height, r is formed when you draw a diagonal in the square)
r = sq rt 144 = 12