​a line is of length 5 and one end is at point (1,-2); if the abscissa of the other end is 4, prove that its ordinate must be 2 or -6.

Let A1, -2 and B4, y be the given points.Now, AB = 5 units4-12 + y+22 = 5      Distance between 2 points x1,y1 and x2,y2  = x2 - x12 + y2 - y124-12 + y+22 = 259 + y2 + 4 + 4y = 25y2 + 4y - 12 = 0y2 + 6y - 2y - 12 = 0yy + 6 - 2y + 6=0y - 2y + 6 = 0y - 2 = 0   or  y+6 = 0y = 2  or  y = -6

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