document.write( "Question 365047: Evening All.
\n" ); document.write( " Struggling on this vectors problem.\r
\n" ); document.write( "\n" ); document.write( "i)If a and b are perpendicular, then by writing a= ¦a¦ and b= ¦b¦ simplify the expression (a-2b).(3a+5b)\r
\n" ); document.write( "\n" ); document.write( "ii)Show that the vectors a=i+2j and b=4i-2j are perpendicular\r
\n" ); document.write( "\n" ); document.write( "iii) Find the angle theta in degrees between the vectors p=i-j-k and q=2i+j+2k\r
\n" ); document.write( "\n" ); document.write( "Many Thanks \n" ); document.write( "

Algebra.Com's Answer #260304 by Edwin McCravy(20060) $\"\"$ $\"About$

You can put this solution on YOUR website!
Struggling on this vectors problem.
\n" ); document.write( "i)If a and b are perpendicular, then by writing a= ¦a¦ and b= ¦b¦ simplify the expression (a-2b).(3a+5b)
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document.write( "Sorry I don't understand \"writing a= ¦a¦ and b= ¦b¦\".  If you\r\n" );
document.write( "can explain what that means I can help you.  Here are the others:\r\n" );
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\n" ); document.write( "ii)Show that the vectors a=i+2j and b=4i-2j are perpendicular
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document.write( "Just show that their dot product (scalar product) is 0:\r\n" );
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document.write( "(i+2j)·(4i-2j) = (1)(4)+(2)(-2) = 4-4 = 0\r\n" );
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\n" ); document.write( "iii) Find the angle theta in degrees between the vectors p=i-j-k and q=2i+j+2k
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document.write( "Use the formula \r\n" );
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document.write( "           u·v \r\n" );
document.write( "cos(@) = ------ =\r\n" );
document.write( "         |u||v|\r\n" );
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document.write( " =\r\n" );
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document.write( " =\r\n" );
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document.write( " =  =  =  =  = \r\n" );
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document.write( "So @ = 101.1° approximately\r\n" );
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document.write( "Edwin

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