The lines 2x = 3y = $$-$$ z and 6x = $$-$$ y = $$-$$ 4z

The radius of the sphere $$3{x^2} + 3{y^2} + 3{z^2} - 8x + 4y + 8z - 15 = 0$$ is

The direction ratios of the line perpendicular to the lines with direction ratios < 1, $$-$$2, $$-$$2 > and < 0, 2, 1 > are

What are the coordinates of the foot of the perpendicular drawn from the point (3, 5, 4) on the plane z = 0 ?