Grade 8/9 question: Point A (0,1) and Point B (10,6) lie on a straight line. Find the equation of the line perpendicular to AB which also intersects B.

Gradient of AB: Change in Y/ Change in X .... (6-1)/(10-0) = 0.5Gradient of line perpendicular to AB: NEGATIVE (flip the sign) RECIPROCAL (flip the fraction) ... -2Equation of line perpendicular and intersecting B: Y = mX + c ... 6 = (-2 x 10) + c .... 6 = -20 + c ... c = 26Answer: y= -2x + 26