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# Class 12-science RD SHARMA Solutions Maths Chapter 27 - Direction Cosines and Direction Ratios

## Direction Cosines and Direction Ratios Exercise Ex. 27.1

### Solution 1

Let l, m and n be the direction cosines of a line.

l = cos 90° = 0

## Direction Cosines and Direction Ratios Exercise MCQ

### Solution 1

Correct option: (c)

Every point on xy-plane z co-ordinate is always zero.

### Solution 2

Correct option: (c)

Point (x, y, z) is on the x-axis. Hence, y and z co-ordinate will be zero except the origin.

### Solution 3

Correct option: (d)

Coordinates of the points given are diagonally opposite vertices of a parallelepiped. Hence, edges of parallelepiped can be 5-2, 7-3, 9-7 3,4,2.

### Solution 4

Correct option : (a)

### Solution 5

Correct option: (b)

### Solution 6

Correct option: (c)

### Solution 7

Correct option: (a)

### Solution 8

Correct option: (b)

### Solution 9

Correct option: (b)

### Solution 10

Correct option: (a)

### Solution 11

Correct option: (a)

Directions of OP from the origin

(-1,2,-2)=(x,y,z)

### Solution 12

Correct option: (d)

### Solution 13

Correct option: (c)

## Direction Cosines and Direction Ratios Exercise Ex. 27VSAQ

### Solution 15

So the projection of the point P on y-axis is (0, -3, 0)