Let u and v be two parallel lines passing through points A=(5,0) and
B=(-5,0) respectively. Let the line 4x+3y=25 meet u at P and v at Q.
a) If the length of PQ is 5 units, describe that there are two possibilities for the pair of parallel lines u and v.
b) Write down the equations of all four lines determined above.
Answer only part b).