Get Answers to all your Questions

header-bg qa

Q5 (2)   In Fig. 6.60, AD is a median of a triangle ABC and  AM \perp BC. Prove that :

 

           AB ^2 = AD ^2 - BC .DM + \left ( \frac{BC}{2} \right ) ^2           

Answers (1)

best_answer

In \triangleABM, by Pythagoras theorem

AB^2=AM^2+MB^2

AB^2=(AD^2-DM^2)+MB^2

\Rightarrow AB^2=(AD^2-DM^2)+(BD-MD)^2

\Rightarrow AB^2=AD^2-DM^2+(BD)^2+(MD)^2-2.BD.MD

\Rightarrow AB^2=AD^2+(BD)^2-2.BD.MD           

\Rightarrow AB^2 = AD^2 + (\frac{BC}{2})^2 -2(\frac{BC}{2}). MD.=AC^2           (BC=2 BD)

\Rightarrow AD^2 + (\frac{BC}{2})^2 -BC. MD.=AC^2

Posted by

seema garhwal

View full answer