NCERT Class 12-Mathematics: Chapter – 11 Three Dimensional Geometry Part 7 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 6:

Prove that the lines and are perpendicular if .


We have,



From Eq. (iii) and (iv) ,


If these given lines are perpendicular to each other, then

Which is the required condition.

Question 7:

Find the equation of a plane which bisects perpendicularly the line joining the points and at right angles.


Question 8:

Find the equation of a plane which is at a distance units from origin and the normal to which is equally inclined to coordinate axis.


Question 9:

If the line drawn from the point meets a plane at right angle at the point , find the equation of the plane.


Question 10:

Find the equation of the plane through the points and .


Question 11:

Find the equations of the two lines through the origin which intersect the line at angle of each.


Question 12:

Find the angle between the lines whose direction cosines are given by the equations .


Eliminating n from both the equations, we have

Thus, Dr՚s two lines are proportional to

So, the vector parallel to these given lines are


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