Lines

Figure shows the lines l1, l2 and l3.

Line l1 passes through the points A (5, 2 ) and B ( 7, 8 ).

a) Find an equation of the line l1

Line l2 is perpendicular to line l1 and also passes through the point A.

b) Find an equation of the line l2

Line l3 has equation x - 2y + 9 = 0 and intersects line l1 at point the B and line l2 at the point C.

c) Find the coordinates of the point C

d) Show that triangle is isosceles.