If the median of △ABC through A is perpendicular to AB prove that tanA+2tanB=0.
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Solution
We are given BD= DC and ∠DAB=900 Draw CN⊥ to BA produced Then in △BCN we have DA=12CN=y and AB=AN =z. ∴tanA=tan(π−∠CAN) =−tan(∠CAN)=−CNAN=−2yz or tanA=−(2AD/AB)=−2tanB or tanA+2tanB=0