Mathematics Part-II

Book: Mathematics Part-II

Chapter: 11. Three Dimensional Geometry

Subject: Maths - Class 12th

Q. No. 13 of Exercise 11.2

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13

Show that the lines are perpendicular to each other.

We know that

Two lines with direction ratios a1, b1, c1 and a2, b2, c2 are perpendicular if the angle between them is θ = 90°, i.e. a1a2 + b1b2 + c1c2 = 0


Also, here the direction ratios are:


a1 = 7, b1 = -5, c1 = 1 and a2 = 1, b2 = 2, c2 = 3


Now, Consider


a1a2 + b1b2 + c1c2 = 7 × 1 + (-5) × 2 + 1 × 3 = 7 -10 + 3 = - 3 + 3 = 0


∴ The two lines are perpendicular to each other.


13

Chapter Exercises

Exercise 11.1
Exercise 11.2
Exercise 11.3
Miscellaneous Exercise

More Exercise Questions

1

Show that the three lines with direction cosines are mutually perpendicular.
2

Show that the line through the points (1, –1, 2), (3, 4, –2) is perpendicular to the line through the points (0, 3, 2) and (3, 5, 6).
3

Show that the line through the points (4, 7, 8), (2, 3, 4) is parallel to the line through the points (–1, –2, 1), (1, 2, 5).
4

Find the equation of the line which passes through the point (1, 2, 3) and is parallel to the vector

5

Find the equation of the line in vector and in cartesian form that passes through the point with position vector and is in the direction

6

Find the cartesian equation of the line which passes through the point (–2, 4, –5) and parallel to the line given by

7

The Cartesian equation of a line is . Write its vector form.
1

Find the vector and the cartesian equations of the lines that passes through the origin and (5, –2, 3).
9

. Find the vector and the cartesian equations of the line that passes through the points (3, –2, –5), (3, –2, 6).
10

Find the angle between the following pairs of lines:
11

. Find the angle between the following pair of lines:
12

Find the values of p so that the lines are at right angles.
13

Show that the lines are perpendicular to each other.
14

Find the shortest distance between the lines
15

Find the shortest distance between the lines
16

Find the shortest distance between the lines whose vector equations are
17

Find the shortest distance between the lines whose vector equations are