Mathematics for IGCSE & O level - Coordinate Geometry (Section 2 - No. 27)
Which of the following accurately represents the relationship between two perpendicular lines?
Their gradients are equal.
The product of their gradients is -1.
Their y-intercepts are the same.
The lines intersect at a right angle.
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Perpendicular lines have gradients that are negative reciprocals of each other, and they intersect at 90 degrees.