Find the foot of the perpendicular from (0, 2, 7) on the line
Given: - Point P(0, 2, 7) and equation of line
Let, PQ be the perpendicular drawn from P to given line whose endpoint/ foot is Q point.
Thus to find Distance PQ we have to first find coordinates of Q
⇒ x = – λ – 2, y = 3λ + 1, z = – 2λ + 3
Therefore, coordinates of Q( – λ – 2, 3λ + 1, – 2λ + 3)
Now as we know (TIP) ‘if two points A(x1,y1,z1) and B(x2,y2,z2) on a line, then its direction ratios are proportional to (x2 – x1,y2 – y1,z2 – z1)’
Hence
Direction ratio of PQ is
= ( – λ – 2 – 0), (3λ + 1 – 2), ( – 2λ + 3 – 7)
= ( – λ – 2), (3λ – 1), ( – 2λ – 4)
and by comparing with given line equation, direction ratios of the given line are
(hint: denominator terms of line equation)
= ( – 1,3, – 2)
Since PQ is perpendicular to given line, therefore by “condition of perpendicularity.”
a1a2 + b1b2 + c1c2 = 0 ; where ‘a’ terms and ‘b’ terms are direction ratio of lines which are perpendicular to each other.
⇒ – 1( – λ – 2) + (3)(3λ – 1) – 2( – 2λ – 4) = 0
⇒ λ + 2 + 9λ – 3 + 4λ + 8 = 0
⇒ 14λ + 7 = 0
⇒
Therefore coordinates of Q
i.e. Foot of perpendicular
By putting the value of λ in Q coordinate equation, we get