Question: Equation of a line (2)

Problem: Let (d): x = 2*t + 3, y = t -2, z = -t -1 be a line and (P): x+ y + z + 2 = 0 be a plane. Write the equation of a line Delta lies in the plane (P), Delta perpendicular to the line (d) and the distance from point M (1,-3, 0) to Delta equal to  sqrt (42). 

This is my idea

Let H(x,y,z) be projection of the point M on the line Delta. We find a, b, c from the following conditions:

1) H lies on (P);

2) Vector(MH) perpendicular to direction vector a = (2, 1, -1) of (d);

3) MH = sqrt(42).

and my code 

restart:

with(LinearAlgebra):

with(geom3d):

line(Delta,[2*t+3,t-2,-t-1],t);

a:=convert(ParallelVector(Delta),Vector);

M:=<x,y,z>;

From here, I do not know how to call H is  projection of M on Delta. Please help me. Thank you very much.