CONCEPT: The angle θ between two lines whose direction ratios are proportional to a1,b1,c1 and a2,b2,c2 respectively is given by: cos‌θ=|‌
a1a2+b1b2+c1c2
√a12+b12+c12√a22+b22+c22
| CALCULATION: Here, we have to find the angle between the two lines having direction ratios (6,3,6) and (3,3,0). Here, a1=6,b1=3,c1=6,a2=3,b2=3 and c2=0 As we know that, if θ is the angle between two lines having directionratios proportional to a1,b1,c1 and a2,b2,c2 is given by: cos‌θ=|‌