Question

solve graphically the pair of Linear equations 3x-4y+3=0 and 3x+4y-21=0 find the coordinates of the vertices of triangular region formed by these lines and X-axis also calculate the area of the triangle

Answer 1

See the diagram.

The intersection point is B (3,3)
The points of intersection of the two lines with x axis are: 
       A(-1,0)     C(7,0).    The altitude of the triangle ABC :  BD = 3 units

Area of ΔABC =  1/2 * 8 * 3 = 12 units