If `D` is the mid point of side BC of a triangle ABC such that ` vec A B+ vec A C=lambda\ vec A D ,` write the value of `lambdadot`

Explanation

We have given

`D`
is the mid point of side BC of a triangle ABC such that ` vec A B+ vec A C=lambda\ vec A D ,`

Where `A` denote `vec a` and `B` denote `vec b` and `C` denote `vec c` and `D` denote `frac{vec b +vecc}{2}`

From given

` vec A B+ vec A C=lambda\ vec A D `

`vec b-vec a +vec c - vec a=lambda(frac{vec b +vecc}{2}-vec a)`

`vec b+vec c-2 vec a=lambda(frac{vec b+vec c-2 vec a}{2})`

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