WEBVTT
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Two lines are perpendicular.
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What will the product of their slopes be?
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Here’s what we know.
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The slope of perpendicular lines are the negative reciprocal of one another.
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The reciprocal is also called the multiplicative inverse.
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And the multiplicative inverse is what you multiply by a number to equal one.
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So two reciprocals multiplied together equal one.
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So when we multiply any slope by its reciprocal, it multiplies together to equal one.
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But we’re dealing with not just reciprocal slopes, but negative reciprocal slopes.
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Perpendicular lines are the negative reciprocal, which means when you multiply a slope by a perpendicular slope, they multiply together to equal negative one.
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For any two lines that are perpendicular, if you multiply their slopes together, they will equal negative one.