Question

The point D lies on the intersection of the line y = 5 and the perpendicular
bisector x − 3y + 9 = 0. Find the coordinates of D im stuck!

Answer 1

If point D is the intersection of the 2 lines, y = 5 and x -3y + 9 = 0 , then call the coordinate of point D is (x',5) (the y coordinate is always 5 from line y = 5), substitue that point D in the second equation , you have

x' - 3(5) + 9 = 0 ==> x' = 6 ...so the coordinate of point D is (6,5)