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mathematicsprinted 61 · PDF 62
165 pagesrevision 46935
printed 61 · PDF 62
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61
When 2 lines are parallel on the cartesian plane, both lines gradient/slope/m are equal.
When 2 lines are perpendicular (intersecting each other at angle of 90), both line
gradients/slope/m whenever multiplied is equal to -1.
(m1)(m2) = -1