find the image of the point ( 1,6,3) inthe line x/1 = y-1/2 = z-2/3. Also write the equation of the line joining the given point and its image and find the length of the segment joining the given point and its image.
Let P (1, 6, 3) be the point whose image is to be determined.
Draw perpendicular from P to the given line which cuts the line L, which is its foot of perpendicular.
Then, image of P will be in The downward direction and at the same distance from L as P.
Let P' (x1, y1, z1) be the image of point P. Then we will find the values of x1, y1, z1.
Then,
Given line is
i.e., the co-ordinate of any general point which lies on the given line is (λ, 2λ + 1, 3λ + 2).
∴ Co-ordinate of L are (λ, 2λ + 1, 3λ + 2).
Now,
Direction ratio's of PL will be
λ – 1, 2λ + 1 – 6, 3λ + 2 – 3 = λ – 1, 2λ – 5, 3λ – 1
Also,
Direction ratio's of given line are 1, 2, 3.
But, PL is perpendicular to the given line.
∴ 1 (λ – 1) + 2 (2λ – 5) + 3 (3λ – 1) = 0
⇒ λ – 1 + 4λ – 10 + 9λ – 3 = 0
⇒ 14λ – 14 = 0
∴ Co-ordinate of L are (1, 3, 5)
Now,
L is the mid point of PP',
By mid point formula
Hence, the image of (1, 6, 3) is (1, 0, 7).