Question by Lê Quốc Trần Anh - Discuss with MathYouLike

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03/08/2017 at 09:04

The bottom of a triangle increases 20%, the height decreases 20%. The area:

A. Don't change

B. Increases 4%

C. Decreases 4%

D. Decreases 10%

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یևσϞջ♱ɮևσϞ➪ȿ₂ 03/08/2017 at 09:27

Call the bottom is a, height is h.

We have : \(\dfrac{a\cdot h}{2}=100\%\)

\(\Leftrightarrow\dfrac{120\%a\cdot80\%h}{2}=96\%\)

So the area decreases by 4%

Choose C.
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