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P6 Circle Problem

• kkhing

  12 Sep 09, 12:33

  The figure shows 3 identical semicircles, a circle and a square OABC enclosed in a bigger semicircle. O is the centre of the bigger semicircle and one of the small semicircles. B is the circle of the circle. Given that AB is 7 cm, find the total area of the shaded parts. (Take pie = 22/7).

  

• Mikethm

  12 Sep 09, 12:38

  area of triangle ABC = 1/2 x 7 x 7 = 24.5

  area of Quadrant ABC = 1/4 x 22/7 x 7^2 = 38.5

  Area of shaded region = 4 x (38.5 - 24.5) = 56 cm^2

• ASKL!

  15 Sep 09, 17:22

  area of triangle 1/2 x 7 x 7 = 24.5
  isn't that the slant height?

• ThunderFbolt

  15 Sep 09, 18:27

  Originally posted by ASKL!:

  area of triangle 1/2 x 7 x 7 = 24.5
  isn't that the slant height?

  area of triangle is 0.5 x base length x height perpendicular to base ah...

• Mikethm

  15 Sep 09, 19:17

  Originally posted by ASKL!:

  area of triangle 1/2 x 7 x 7 = 24.5
  isn't that the slant height?

  ABCD is a square. Therefore angle ABC = 90.

  AB(Height) = 7 and AC(Base) = 7