JEE MAIN - Mathematics (2016 - 10th April Morning Slot - No. 13)

ABC is a triangle in a plane with vertices

A(2, 3, 5), B(−1, 3, 2) and C($$\lambda $$, 5, $$\mu $$).

If the median through A is equally inclined to the coordinate axes, then the value of ($$\lambda $$3 + $$\mu $$3 + 5) is :
1130
1348
676
1077

Explanation

JEE Main 2016 (Online) 10th April Morning Slot Mathematics - 3D Geometry Question 286 English Explanation

DR's of AD are

$${{\lambda - 1} \over 2} - 2,{{5 + 3} \over 2} - 3,{{\mu + 2} \over 2} - 5$$

i.e.  $${{\lambda - 5} \over 2},\,\,1,\,\,{{\mu - 8} \over 2}$$

As medium is making equal angles with coordinate axes,

$$ \therefore $$   $${{\lambda - 5} \over 2} = 1 = {{\mu - 8} \over 2}$$

$$ \Rightarrow $$   $$\lambda $$ = 7,   $$\mu $$ = 10

$$ \therefore $$   $$\lambda $$3 + $$\mu $$3 + 5 = 73 + 103 + 5 = 1348

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