Let P be a plane in space and let v be a vector. The vector projection of v onto the plane P, proj_P v, can be defined informally as follows. Suppose the sun is shining so that its rays are normal to the plane P. Then proj_P v is the “shadow” of v onto P. If P is the plane x + 2y + 6z = 6 and v = i + j + k, find proj_P v.