There is an intuitive definition of perpendicularity. It does not involve angle. Instead, it involves the notion of distance. Consider a point P and a line L not passing through it. If you wish to walk from P to L, the path of shortest distance is the perpendicular drawn from P to L.

This idea is used in the following problem, (similar to a problem from AMC – American Mathematical Contest 10 A, 2018).

Part 1

Part 2

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1 Comment

Gopal Roy on August 14, 2018 at 1:45 pm

Sir ,is an another way of solution of this problem(AMC 10A,2018).I send you my solution through Skype.

Sir ,is an another way of solution of this problem(AMC 10A,2018).I send you my solution through Skype.