Question 951170
The opposite reciprocal is the negative of the reciprocal.
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For two lines to be perpendicular the product of the slopes must be -1.
m1*m2 = -1 so m1(-1/m1) = -1
So m2 = -1/m1
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If one of the slopes is 2 the other must be -1/2
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Cheers,
Stan H.