Find the angle between the line joining the points (3, – 4, – 2) and (12, 2, 0) and the plane 3x – y + z = 1.

As we know that the angle θ between the line and a plane a2x + b2y + c2z + d2 = 0 is given by

……(1)


Given that the line is passing through A(3, – 4, – 2) and (12, 2, 0)


the direction ratios of line AB are


= (12 – 3, 2 – (– 4), 0 – (– 2))


= (12 – 3, 2 + 4, 0 + 2)


= (9, 6, 2)


So,


a1 = 9, b1 = 6 and c1 = 2 ……(2)


Given equation of plane is 3x – y + z = 1


So,


a2 = 3, b2 = – 1 and c2 = 1 ……(3)





θ = sin – 1 ()


Therefore the required angle is sin – 1 ()


3