Sunday, March 28, 2010

Area P5 2009 SA1 P2 MGS Q3

3. In the diagram below, ABCD is a square. AC = 18 cm. Find the area of the triangle ABC.


Area of triangle ABC = ½ x 18 x (½ x 18).
1/2 x 18 x 1/2 x 18 = 81 cm2
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1 comment:

  1. AnonymousSeptember 8, 2010 at 12:22 PM

    Because of pythorgas theorm:
    (adjacent side)^2+(opposite side)^2=(long side)^2 in any right angle triangle,
    (Line AB)^2+(Line BC)^2=(18cm)^2
    =324cm2
    (Line AB)^2=(Line BC^2), so
    2 Line AB^2=324cm2
    Line AB^2=162cm2
    Line AB=sqrt(162cm2)
    Line BC=sqrt(162cm2)
    Area of triangle ABC=1/2xBCxAB
    =1/2xsqrt(162cm2)^2
    =1/2x162cm2
    =81cm2

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