document.write( "Question 1152146: Find all solutions of the equation \"cos+3x+=+cos+x\" in the interval [0,2pi) \n" ); document.write( "
Algebra.Com's Answer #774105 by math_helper(2461)\"\" \"About 
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One way is to graph cos(x) and cos(3x) on [0,2pi) and see where the graphs have the same y-value:
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\n" ); document.write( "\n" ); document.write( "Another way is to graph cos(x) - cos(3x) and look for points where this difference function crosses, or touches, the x-axis:\r
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\n" ); document.write( "From the difference function, we see 0, pi/2, pi, and 3pi/2 are solutions.\r
\n" ); document.write( "\n" ); document.write( "Check:
\n" ); document.write( "cos(0) = cos(3*0) = 1
\n" ); document.write( "cos(pi/2) = cos(3pi/2) = 0
\n" ); document.write( "cos(pi) = cos(3pi) = -1
\n" ); document.write( "cos(3pi/2) = cos(9pi/2) = 0\r
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