Find the value of m for which the lines 4x -3y - 1 = 0, 3x - 4y + 1 = 0 and mx - 7y + 3 = 0 are concurrent.

Without solving the equations show that the straight lines 4x - y + 2 = 0, 3x + 2y -1 = 0 and x - 3y + 3 = 0 are concurrent.

Find the value of k for which the lines 5x + 4y - 6 = 0 and 2x + ky + 9 = 0 are (i) parailel,

Find the value of k for which the lines 5x + 4y - 6 = 0 and 2x + ky + 9 = 0 are (ii) perpendicular.

Prove that the straight lines y - x + 1 = 0, 2y - x - 1 = 0 and 7x -y - 19 = 0 are concurrent.

Find the acute angle between the lines x - sqrt3 y = 1 and sqrt3 x -y = 4

Find the angle between the lines x-sqrt 3y=1 and sqrt 3x-y=1 .

Find the equation of straight line passing through the point of intersection of the straight lines 2x - 3y + 4 = 0 and x + 2y - 5 = 0 and perpendicular to the line 3x - 4y + 5 = 0.

Find the derivate of : y = sin^-1(3x-4x^3)