document.write( "Question 873027: Solve the multi-angle below\r
\n" ); document.write( "\n" ); document.write( "sin(2x)= - square root of 2 / 2
\n" ); document.write( "

Algebra.Com's Answer #526638 by KMST(5328)\"\" \"About 
You can put this solution on YOUR website!
If \"sin%282x%29=+-sqrt%282%29%2F2\" It could be that \"2x=-pi%2F4\" or \"2x=-3pi%2F4\" (for angles \"AOP\" and \"AOQ\" ).
\n" ); document.write( " \"2x\" could also be any other angle differing from those by a multiple of \"2pi\" .
\n" ); document.write( "Starting from \"2x=-pi%2F2+%2B-+pi%2F4\"=\"system%282x=-pi%2F4%2C%22or%22%2C2x=-3pi%2F4%29\" ,
\n" ); document.write( "or from \"2x=3pi%2F2+%2B-+pi%2F4\"=\"system%282x=5pi%2F4%2C%22or%22%2C2x=7pi%2F4%29\"
\n" ); document.write( "a way of expressing all those angle with one formula is
\n" ); document.write( "\"2x=%282k%2Api-pi%2F2%29+%2B-+pi%2F4=8k%2Api%2F4-2pi%2F4+%2B-+pi%2F4=%288k-2+%2B-+1%29pi%2F4\" for any integer \"k\" .
\n" ); document.write( "So \"2x=%288k-2+%2B-+1%29pi%2F4\" ---> \"highlight%28x=%288k-2+%2B-+1%29pi%2F8%29\" for any integer \"k\" .
\n" ); document.write( "That gives you infinite pairs of co-terminal angles:
\n" ); document.write( "For \"k=-1\" we have \"x=-11pi%2F8\" and \"x=-9pi%2F8\" .
\n" ); document.write( "For \"k=0\" we have \"x=-3pi%2F8\" and \"x=-pi%2F8\" .
\n" ); document.write( "For \"k=1\" we have \"x=5pi%2F8\" and \"x=7pi%2F8\" .
\n" ); document.write( "For \"k=2\" we have \"x=13pi%2F8\" and \"x=15pi%2F8\" .
\n" ); document.write( "There are infinitely more pairs.
\n" ); document.write( "
\n" );