# Direction cosines of a vector

- Author:
- Krishna Bahadur Bista

- Topic:
- Cosine

## Direction Cosines of a vector

Let be any vector making the angles , and with the positive X-,Y- and Z- axes respectively. Then the cosines of the angles , and are called the direction cosines of the vector . They are denoted by l = cos , m =cos and n = cos . If = (x,y,z) then cos = , cos = and cos = where, , and are the x-,y- and z- component of the unit vector in the direction of the vector .