Let A D and B C be two vertical poles at A   and   B respectively on a horizontal ground. If A D =…

Let AD and BC be two vertical poles at A and B respectively on a horizontal ground. If AD=8m, BC=11m, AB=10m; then the distance (in meters) of a point M lying in between  AB from the point A such that MD2+MC2 is minimums, is__

Solution

Let AM=x and S=MD2+MC2

So, MD2+MC2=64+x2+121+(10-x)2

S=285-20x+2x2

dSdx=-20+4xdSdx=0x=5

d2Sdx2=4=+ve

Asked in: JEE Main 2020 (06 Sep Shift 1)

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