document.write( "Question 110696This question is from textbook
\n" ); document.write( ": Line A goes through the points (2, #) and (-4, 21). Line B goes through the points (4, -1) and (10, 1). Are these two lines parallel, perpendicular, or neither? \n" ); document.write( "

Algebra.Com's Answer #80670 by solver91311(24713) $\"\"$ $\"About$

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I'm going to assume that you meant point (2,3) for the first point of line A since '#' is Shift-3.
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\n" ); document.write( "Step 1 is to calculate the slopes of each line:
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\n" ); document.write( " $\"m%5BA%5D=%2821-3%29%2F%28-4-2%29=18%2F-6=-3\"$ , and
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\n" ); document.write( " $\"m%5BB%5D=%281-%28-1%29%29%2F%2810-4%29=2%2F6=1%2F3\"$
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\n" ); document.write( "Line A is parallel to line B if and only if $\"m%5BA%5D=m%5BB%5D\"$ , but $\"-3%3C%3E1%2F3\"$ so line A is NOT parallel to line B.
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\n" ); document.write( "Line A is perpendicular to line B if and only if $\"m%5BA%5D=-1%2Fm%5BB%5D\"$ . Since $\"-3=%28-1%29%2F%281%2F3%29\"$ , line A IS perpendicular to line B.
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\n" ); document.write( "And they look perpendicular to me.
\n" ); document.write( " $\"graph%28400%2C400%2C0%2C6%2C-3%2C3%2C%28-3%29x%2B9%2C%281%2F3%29x-%287%2F3%29%29\"$
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\n" ); document.write( "Extra credit: Write back and tell me which line, red or green, is Line A. \n" ); document.write( "

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