Most Important Selected Qs for JEE AdvancedMathematicsThree Dimensional Geometry
D-A B C is a tetrahedron with A=(2,0,0), B=(0,4,0) and C D= 14 . Edge C D lies on the line x-1 1 = y-1 2 = z-3 3 . If locus of centroid of tetrahedron is x- 3 2 1 = y-y₁ a = z-z₁ b , then which of the following is/are true:
Options
- Aa+b=5
- By₁+z₁=6
- Cy₁-z₁=1
- Da+b+y₁=8
Correct answer
D. a+b+y₁=8
Step-by-step solution
Let C= ( ₁+1,2 ₁+2,3 ₁+3 ) and D= ( ₂+1,2 ₂+2,3 ₂+3 ) C D= 14 ( ₁- ₂ )= 14 ₁= ₂+1 Locus is 4 x-5 2 = 4 y-10 4 = 4 z-9 6 Dr's of line 1,2,3 and point ( 3 2 , 3,3 ) satisfies the line Locus is x- 3 2 1 = y-3 3 = z-3 3