1)

If a line makes angle 1200 and 600 with the positive directions of X and Z -axes respectively, then the angle made by the line  with a positive Y-axis is 


A) 1500

B) 600

C) 1350

D) 1200

Answer:

Option C

Explanation:

Let angles α,β,γ  makes positive direction of X,Y and Z  axes, respectively,

     cos2α+cos2β+cos2γ=1

Here, α1200   and γ =600

    cos21200+cos2β+cos2600=1

   (12)2+cos2β+(12)2=1

    cos2β=112=12

     cosβ=±12

   β=1350