Let P be the point (10, -2, -1) and Q be the foot of the perpendicular drawn from the point R(1, 7, 6) on the line passing through the points (2, -5, 11) and (-6, 7, -5). Then the length of the line segment PQ is equal to .
Answer
13
Solution
[figure]
D.r. of the line (-8, 12, -16) (2, -3, 4)
Q = (2 + 2 , -5 - 3 , 11 + 4 )
RQ = (1 + 2 , -12 - 3 , 5 + 4 ) line:
2(1 + 2 ) - 3(-12 - 3 ) + 4(5 + 4 ) = 0 58 + 29 = 0 = -2
Q = (-2, 1, 3)
PQ = 122 + 32 + 42 = 169 = 13
Answer: 13