K KingAce New member Joined Oct 12, 2006 Messages 44 Sep 17, 2009 #1 Find all solutions on interval [0, 2pi] for cos(x)+sin(2x)=0 I need a refresher; I have an exam coming up, and I've forgotten how to do these type of problems. Please help! Thanks!
Find all solutions on interval [0, 2pi] for cos(x)+sin(2x)=0 I need a refresher; I have an exam coming up, and I've forgotten how to do these type of problems. Please help! Thanks!
pka Elite Member Joined Jan 29, 2005 Messages 11,978 Sep 17, 2009 #2 \(\displaystyle \begin{array}{l} \cos (x) + \sin (2x) = 0 \\ \cos (x) + 2\sin (x)\cos (x) = 0 \\ \cos (x)\left( {1 + 2\sin (x)} \right) = 0 \\ \end{array}\)
\(\displaystyle \begin{array}{l} \cos (x) + \sin (2x) = 0 \\ \cos (x) + 2\sin (x)\cos (x) = 0 \\ \cos (x)\left( {1 + 2\sin (x)} \right) = 0 \\ \end{array}\)
