document.write( "Question 396290: Hi, I am stuggling very much on these two questions on complex numbers. If you can help, it would be very much appreciated. Thank you!\r
\n" ); document.write( "\n" ); document.write( "Directions: In these questions exact values for θ are to be used and answers are to be expressed as a radical.\r
\n" ); document.write( "\n" ); document.write( "1. If z=10(cos225°+i*sin225°) in trigonometric form find z in standard form.\r
\n" ); document.write( "\n" ); document.write( "2. If z=6sqrt(3)(cos330°+i*sin330°) in trigonometric form find z in standard form.
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Algebra.Com's Answer #281147 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
I'm guessing that what you're really having
\n" ); document.write( "problems with is trig. Do you have a solid foundation
\n" ); document.write( "in trig? Can you easily convert cos 225 degrees to
\n" ); document.write( "an expression with radicals?
\n" ); document.write( "\"225+=+180+%2B+45\" degrees, so you have a vector in
\n" ); document.write( "the 3rd quadrant where the cosine and sine are both negative
\n" ); document.write( "\"cos%28225%29+=+-+1%2Fsqrt%282%29\"
\n" ); document.write( "\"sin%28225%29+=+-+1%2Fsqrt%282%29\"
\n" ); document.write( "(1)
\n" ); document.write( "\"z+=+10%2A%28-1%2Fsqrt%282%29+-+i%2A%281%2Fsqrt%282%29%29%29\"
\n" ); document.write( "\"z+=+%2810%2Fsqrt%282%29%29%2A%28-1+-+i%29\"
\n" ); document.write( "Multiply top and bottom by \"sqrt%282%29\"
\n" ); document.write( "\"z+=+5%2Asqrt%282%29%2A%28-1+-+i%29\"
\n" ); document.write( "------------------------------
\n" ); document.write( "Note also that
\n" ); document.write( "\"cos%28330%29+=+cos%28360+-+30%29\"
\n" ); document.write( "So the angle is in the 4th quadrant and makes
\n" ); document.write( "an angle of 30 with the positive real axis.
\n" ); document.write( "The cosine is positive and the sine is negative
\n" ); document.write( "\"cos%28330%29+=+sqrt%283%29%2F2\"
\n" ); document.write( "\"sin%28330%29+=+-1%2F2\"
\n" ); document.write( "You can finish as I did in (1)
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