of contact of tangent line AB with the circle. Solution (i) Equation of line AB, A ( , ) and B ( , ) y - = y - = − x ⇒ y – = – x x + y – = (ii) The equation of a line which is perpendicular to the line AB : x is x k = Since it is passing through the point ( , ) , we have – + k = ⇒ k = The equation of a line which is perpendicular to AB and through C is x = (iii) The coordinate of the point of contact P of the tangent line AB with the circle is point of intersection of lines. and x = solving, we get x = and y = Therefore, the coordinate of the point of contact is P . Activity Find the equation of a straight line for the given diagrams X X ′ - ¢ Fig.
Find the number of point of intersection of two straight lines. . Find the number of straight lines perpendicular to the line Coordinate Geometry Exercise . .
Find the slope of the following straight lines (i) y − (ii) x − . Find the slope of the line which is (i) parallel to y (ii) perpendicular to the line x = − . Check