Vector Geometry - relation between a point and a line with angle and one known point on it
I have 2 problems I will be very grateful if somebody helps me about them. If I have a line 'L1' with a known point (x1, y1) on it and has an angle 'theta1', how do I know if a point 'P' (x, y) is right to it or left? Or upper or lower? 

The second problem, if I get the distance between the previous point 'P' and the previous line 'L1' as 'd = sqrt((x-x1)*(x-x1) + (y-y1)*(y-y1))', how can I relocate 'P' to a different line 'L2' with a known point (x2, y2) on it and has an angle 'theta2' keeping the same distance between the new point and 'L2', so what's the new (x, y) for point 'P'?

I don't have much experience in Vectors and any help will be much appreciated.

Many thanks,
Vector Geometry - relation between a point and a line with angle and one known point on it
===

I have 2 problems I will be very grateful if somebody helps me about them. If I have a line 'L1' with a known point (x1, y1) on it and has an angle 'theta1', how do I know if a point 'P' (x, y) is right to it or left? Or upper or lower? 

The second problem, if I get the distance between the previous point 'P' and the previous line 'L1' as 'd = sqrt((x-x1)*(x-x1) + (y-y1)*(y-y1))', how can I relocate 'P' to a different line 'L2' with a known point (x2, y2) on it and has an angle 'theta2' keeping the same distance between the new point and 'L2', so what's the new (x, y) for point 'P'?

I don't have much experience in Vectors and any help will be much appreciated.

Many thanks,