Mathematics

Two lines in 3D intersect when they meet at a single point—meaning there's a value of the parameter on each line that produces the same $(x, y, z)$ coordinates. Set up parametric equations for both lines, then use the fact that at intersection, all three coordinates must match simultaneously. This gives you a system of equations to solve for both parameters and the unknown $a$.

Two lines in 3D intersect when they meet at a single point—meaning there's a value of the parameter on each line that produces the same $(x, y, z)$ coordinates. Set up parametric equations for both lines, then use the fact that at intersection, all three coordinates must match simultaneously. This gives you a system of equations to solve for both parameters and the unknown $a$.