document.write( "Question 395841: Hi, I have a big test on complex numbers tomorrow and I am having a very hard time with this particular question:\r
\n" ); document.write( "\n" ); document.write( "Directions: On a complex plane, a point z has been graphed. your\r
\n" ); document.write( "\n" ); document.write( "If cosθ=(-8)/(22) and (π)/(2)≤θ≤π:\r
\n" ); document.write( "\n" ); document.write( "a) Find z in standard form.
\n" ); document.write( "b) Find z in trigonometric form. (Use whole degrees)\r
\n" ); document.write( "\n" ); document.write( "θ= Theta
\n" ); document.write( "π= pi
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Algebra.Com's Answer #280964 by richard1234(7193)\"\" \"About 
You can put this solution on YOUR website!
The angle is in the second quadrant, so \"sin+%28theta%29\" is positive. By the Pythagorean identity,\r
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\n" ); document.write( "\n" ); document.write( "\"sin%5E2+%28theta%29+%2B+cos%5E2+%28theta%29+=+1\"\r
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\n" ); document.write( "\n" ); document.write( "\"sin%5E2+%28theta%29+%2B+16%2F121+=+1\"\r
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\n" ); document.write( "\n" ); document.write( "\"sin%5E2+%28theta%29+=+105%2F121\"\r
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\n" ); document.write( "\n" ); document.write( "\"sin+%28theta%29+=+sqrt%28105%29%2F11\"\r
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\n" ); document.write( "\n" ); document.write( "Since the cosine corresponds to the x-coordinate or the real part of z, we say that \"Re%28z%29+=+4%2F11\". Likewise, \"Im%28z%29+=+%28sqrt%28105%29%2F11%29i\", so the complex number is \"z+=+4%2F11+%2B+%28sqrt%28105%29%2F11%29i\". Note that we can multiply z by any real constant and the cosine, sine values will still be the same.
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