## Question

primary 5 | Maths | Angles & Geometry

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##### Ricky

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Date Posted: 10 months ago
Views: 104
Snell
10 months ago
triangle ADE = 0.5 x AG x AE
= 0.5 x AG x 30
= 15 x AG

= 0.5 x 24 x 24 = 288

15 x AG = 288
AG = 19.2 cm

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1st
Hope this helps
Date Posted: 10 months ago
Ricky
10 months ago
AC Lim
10 months ago
Is 1/2 x AD x dotted line (90 deg with AD )
Dotted line = DC = 24 since it is square.
(Triangle Area = 1/2 x base x height. Base and height should be perpendicular, 90deg) Hope this clear your doubts.
AC Lim
10 months ago
At the same time, area ADE also = 1/2 x AE x yellow line (perpendicular height)
Yellow line = AG. Where you can find Length AG.
Eric Nicholas K
10 months ago
Ricky, area of a triangle is

1/2 x base x perpendicular height

Note the word “perpendicular”. That is, the height chosen must be at right angles (90 degrees) to your chosen base. Lengths DE and AD are not at 90 degrees to each other considering that ABCD is a square.

So it is obviously not 1/2 x AD x DE.

AC Lim’s workings are fully correct.