Teo Jer Rei's answer to Catherine Wee Mui Chin's Primary 5 Maths Area & Volume Singapore question.
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For question 5, correct answer should be
1) find area of the big square 10x10=100cm^2
2) find area of small shaded square 5x5=25cm^2
3) find area of the two shaded triangles
(1/2 x 5 x 10) x 2 = 50cm^2
4) take big square area minus the 3 shaded objects
100 - 50 - 25 = 25cm^2
Your working should not have 1/2 x 10 x 10 because that is the area of a triangle with width and height 10cm, which does not exist. (The shaded triangles have width 5cm, height 10cm)
Hope this helps :)
1) find area of the big square 10x10=100cm^2
2) find area of small shaded square 5x5=25cm^2
3) find area of the two shaded triangles
(1/2 x 5 x 10) x 2 = 50cm^2
4) take big square area minus the 3 shaded objects
100 - 50 - 25 = 25cm^2
Your working should not have 1/2 x 10 x 10 because that is the area of a triangle with width and height 10cm, which does not exist. (The shaded triangles have width 5cm, height 10cm)
Hope this helps :)
Date Posted:
2 years ago
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