Question 499185
Two perpendicular lines can be viewed as the x-axis and y-axis, by definition.
(1) Yes, they are at right angles, by definition.
(2) The lines always cross at the point (0,0), so in a sense they're always at the same difference relative to one another.
(3) The sum of the angles where they meet is not 900 degrees; it is 360 degrees.
(4) If one is horizontal, then the other is vertical, by definition.
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The false statement is (3).