Question 12 Marks
In ΔABC, point M is the midpointof side BC.
If, $AB ^2+ AC ^2=290 cm^2, AM =8 cm, BM = MC$

If, $AB ^2+ AC ^2=290 cm^2, AM =8 cm, BM = MC$

Answer
View full question & answer→Given $AB ^2+ AC ^2=290 cm^2, AM =8 cm, BM = MC$
According to formula,
$ AM ^2=\frac{A B^2+A C^2}{2}-\frac{B C^2}{4} $
$ \Rightarrow 64=\frac{290}{2}-\frac{B C^2}{4} $
$ \Rightarrow 64-\frac{290}{2}=-\frac{B C^2}{4}$
$\Rightarrow B C^2=324$
BC = 18.
Thus BC = 18 cm.
According to formula,
$ AM ^2=\frac{A B^2+A C^2}{2}-\frac{B C^2}{4} $
$ \Rightarrow 64=\frac{290}{2}-\frac{B C^2}{4} $
$ \Rightarrow 64-\frac{290}{2}=-\frac{B C^2}{4}$
$\Rightarrow B C^2=324$
BC = 18.
Thus BC = 18 cm.







