Let P and Q be the points on the line x+38= y-42= z+12 which are at a distance of 6 units from the point R(1,2,3). If the centroid of the triangle PQR is ( , , ), then 2+ 2+ 2 is :
- 18
- 24
- 26
- 36
Answer
(1) 18
Solution
General point on the line: (8 -3, 2 +4, 2 -1)
Distance from R(1,2,3) is 6:
(8 -4)2+(2 +2)2+(2 -4)2=36
72 2-72 +36=36 ( -1)=0
(-3,4,-1), Q(5,6,1)
Centroid = ( -3+5+13, 4+6+23, -1+1+33 )=(1,4,1)
2+ 2+ 2=1+16+1=18
Answer: (1)