Let the intersection point of a plane and a line be p(x,y,z). Coordinate of P=(
2×3+1×(−3)
2+1
,
2×1+1×(−2)
2+1
,
2×(−2)+1×7
2+1
) =(1,0,1) DE′s of line AB is 3−(−3),1−(−2),−2−7 =<6,3,−9> Equation of plane is 6(x−1)+3(y−0)−9(z−1)=0 ⇒ 6x−6+3y−9z+9=0 ⇒ 6x+3y−9z=−3 ⇒