MCQ
In Triangle $ABC$ which is right angled at $B.$ Given that $AB = 9\ cm, AC = 15\ cm$ and $D, E$ are the mid-points of the sides $AB$ and $AC$ respectively. Find the length of $BC?$
- A$13\ cm$
- ✓$12\ cm$
- C$15\ cm$
- D$13.5\ cm$
✓
Answer
Correct option: B.
$12\ cm$
Applying Pythagoras theorem in $\triangle\text{ABC}$
$A C^2=A B^2+B C^2$
$15^2=9^2+B C^2$
$225=81+\mathrm{BC}^2$
$225-81=\mathrm{BC}^2$
$B C^2=144$
$B C=12 \mathrm{~cm}$
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