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 CExplanation:Let angles α,β,γ makes positive direction of X,Y and Z axes, respectively, ∴ cos2α+cos2β+cos2γ=1 Here, α= 1200 and γ =600 ∴ cos21200+cos2β+cos2600=1 ⇒ (12)2+cos2β+(12)2=1 ⇒ cos2β=1−12=12 ⇒ cosβ=±1√2 ⇒ β=1350