Theory question 102
Coordinate GeometryGiven that (5, 2), (−4, k) and (2, 1) lie on a straight line, find the value of k.
Show the model answer
Model answer
Gradient from (5, 2) to (2, 1) = 1/3.
(k − 2)/(−4 − 5) = 1/3, so k − 2 = −3 and k = −1.
Explanation
Points on one line have equal gradients between any pair.