Q.

A line makes angles of 45° and 60° with the positive axis of X and Y respectively. The angle made by the same line with the positive axis of Z, is:

1 30° or 60°  
2 60° or 90°  
3 90° or 120°  
4 60° or 120°  

Ans.

(4)

Ans.            60° or 120°

Explanation:

Given     α=45°,  β=60°,  γ=?

∵     cos2α+cos2β+cos2γ=1

∴                                     cos2γ=1-12-14=14

⇒                                              γ=60° or 120°