Angle Between the lines

Find the angle between the lines
x-2/3 = y+1/-2, z=2 and
x-1/1 = 2y+3/3 = z+5/2

This question came in my 12th board and I lost 1 mark in it [2]
Again this question came while taking coaching. I have one doubt
z=2 is a plane....not a line and the question asks to find the angle between the lines.
you can also see a comma after x-2/3 = y+1/-2 which means there are 2 lines and 1 plane.
My Sir just after the exam was over told that you have to take z-2/0 ( which I took as z-2/1)

Explain me why the direction ratio is 0 and not 1?

1 Answers

3
Abhishek Majumdar ·

its pretty simple:-

z=2 after the comma suggests that the z coordinate of the point on the line is always =2 irrespective of the x and y coordinates!!

Lets simply things...:)

we take x-2/3=y+1/-2=z-2/0 (as your teacher told u ) =λ(say)

thus x=3λ+2,y=-2λ-1 , z=2 which does not hamper the given data!

but if we take z-2/1 then though we get the same x and y coordinates in terms of λ, z becomes=λ+2 that is z is not =2 which contradicts your given data

thus it will be z-2/o :)

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