Mathematics for IGCSE & O level - Coordinate Geometry (Section 1 - No. 19)
Which equations represent a line perpendicular to y = (1/2)x + 3?
y = -2x + 1
y = 2x - 3
2y = -4x + 6
y = -x + 3
הֶסבֵּר
Perpendicular lines have negative reciprocal gradients. The negative reciprocal of 1/2 is -2. Therefore lines with -2 as a gradient or equivalent are perpendicular