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).

 

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