Question

The direction cosines of the z-axis is equal to

• A. $0,0,1$
• B. $0,1,0$
• C. $1,0,0$
• D. $0,1,1$

Answer 1

The correct option is A $0,0,1$

We know that the direction cosines of any line are the cosines of the angles it makes from the positive direction of coordinate axes. z- axis is perpendicular to both X & Y axes so makes ${90}^{\circ }$ with both the axes. Whereas with Z - axis it makes $0^{\circ }$ . So, the direction cosines will be - $cos{90}^{\circ }$, $cos{90}^{\circ }$, $cos{0}^{\circ }$.
Or 0, 0, 1.