document.write( "Question 1017539: If sin A = sqrt(10)/10 with A in QI and tan B = 4/3 with B in QI, find tan(A + B) and cot(A + B).\r
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Algebra.Com's Answer #633818 by MathTherapy(10552)\"\" \"About 
You can put this solution on YOUR website!
If sin A = sqrt(10)/10 with A in QI and tan B = 4/3 with B in QI, find tan(A + B) and cot(A + B).\r
\n" ); document.write( "\n" ); document.write( "Note: Ok for this question, I used cos A= sqrt(1-sin A^2) and got sqrt((10-sqrt10)/10). I am confused on how to get rid of the square root. Or can i square both sides? Thank you.
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My question is: Why do you need cos A?.
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document.write( "To find tan (A + B) and cot (A + B), you only need: tan A and tan B, since \"tan+%28A++%2B+B%29+=+%28tan+%28A%29+%2B+tan+%28B%29%29%2F%281+-+tan+%28A%29+tan+%28B%29%29\", and \"cot+%28A+%2B+B%29+=+1%2Fcot+%28A+%2B+B%29\"
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document.write( "\"sin+%28A%29+=+sqrt%2810%29%2F10\"
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document.write( "\"sin+%28A%29+=+sqrt%2810%29%2F10+=+y%2Fr\", so y = \"sqrt%2810%29\", while r = 10
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document.write( "To find x, we get: \"x%5E2+=+r%5E2+-+y%5E2\" ------> \"x%5E2+=+10%5E2+-+%28sqrt%2810%29%29%5E2\" ------> \"x%5E2+=+100+-+10\", or \"x+=+sqrt%2890%29\", or \"x+=+3sqrt%2810%29\"
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document.write( "Now you have: \"tan+%28A%29+=+y%2Fx+=+sqrt%2810%29%2F3sqrt%2810%29\", or \"highlight_green%28tan+%28A%29+=+1%2F3%29\"\r
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document.write( "\"matrix%281%2C5%2Ctan+%28B%29%2Cis%2Cgiven%2Cas%2C4%2F3%29\", so now you have all you need to find what you're looking for. \n" );
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