Answer:
Option A
Explanation:
Equation of plane passing through any three given point is
[x−x1y−y1z−z1x2−x1y2−y1z2−z1x3−x1y3−y1z3−z1]
Points are (-2,6,-6),(-3,10,-9) and (-5,0,-6)
⇒ [x+2y−6z+6−14−3−3−60]=0
⇒ (x+2)(0−18)−(y−6)(0−9)+(z+6)(6+12)=0
⇒ −18(x+2)+9(y−6)+18(z+6)=0
⇒ −18x+9y+18z=36+54−108
⇒ −2ˆi+ˆj+2ˆk=−2
⇒ 2ˆi−ˆj−2ˆk=2
∴ r.(2ˆi−ˆj−2ˆk)=2