document.write( "Question 870609: Find all solutions in the interval [0, 2pi) for the equation sin^2θ=cos^2θ-1 \n" ); document.write( "
Algebra.Com's Answer #525009 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! I'm going to use the variable x instead of the variable θ\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Solve for x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "sin^2(x)=cos^2(x)-1 \n" ); document.write( "sin^2(x)-cos^2(x) = -1 \n" ); document.write( "-1(-sin^2(x)+cos^2(x)) = -1 \n" ); document.write( "-sin^2(x)+cos^2(x) = 1 \n" ); document.write( "cos^2(x)-sin^2(x) = 1 \n" ); document.write( "cos(2x) = 1 \n" ); document.write( "2x = arccos(1) \n" ); document.write( "2x = 0+2pi*n \n" ); document.write( "2x = 2pi*n \n" ); document.write( "x = 2pi*n/2 \n" ); document.write( "x = pi*n\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "All solutions for x are generated by x = pi*n where n is an integer\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If n = -1, then \n" ); document.write( "x = pi*n \n" ); document.write( "x = pi*(-1) \n" ); document.write( "x = -pi ... not in the interval [0, 2pi), so we ignore it\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If n = 0, then \n" ); document.write( "x = pi*n \n" ); document.write( "x = pi*0 \n" ); document.write( "x = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If n = 1, then \n" ); document.write( "x = pi*n \n" ); document.write( "x = pi*1 \n" ); document.write( "x = pi\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If n = 2, then \n" ); document.write( "x = pi*n \n" ); document.write( "x = pi*2 \n" ); document.write( "x = 2pi ... not in the interval [0, 2pi), so we ignore it\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "==============================================================================================================\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The only two solutions are x = 0, x = pi (both in radians) \n" ); document.write( " \n" ); document.write( " |