document.write( "Question 1138070: solve 4 cos^2 θ + 2 sin θ = 3 for 0° ≤ θ ≤ 360° \n" ); document.write( "
Algebra.Com's Answer #755963 by Theo(13342)\"\" \"About 
You can put this solution on YOUR website!
your equation is:\r
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\n" ); document.write( "\n" ); document.write( "4 * cos^2(t) + 2 * sin(t) = 3\r
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\n" ); document.write( "\n" ); document.write( "since cos^2(t) is equal to 1 - sin^2(t), this equation can be shown as:\r
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\n" ); document.write( "\n" ); document.write( "4 * (1 - sin^2(t)) + 2 * sin(t) = 3\r
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\n" ); document.write( "\n" ); document.write( "simplify to get:\r
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\n" ); document.write( "\n" ); document.write( "4 - 4 * sin^2(t) + 2 * sin(t) = 3\r
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\n" ); document.write( "\n" ); document.write( "subtract 3 from both sides of this equation to get:\r
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\n" ); document.write( "\n" ); document.write( "-4 * sin^2(t) + 2 * sin(t) + 1 = 0\r
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\n" ); document.write( "\n" ); document.write( "let x = sin(t) and this equation becomes:\r
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\n" ); document.write( "\n" ); document.write( "-4 * x^2 + 2 * x + 1 = 0\r
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\n" ); document.write( "\n" ); document.write( "factor this quadratic equation to get:\r
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\n" ); document.write( "\n" ); document.write( "x = 0.80901699437495 or x = -0.30901699437495\r
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\n" ); document.write( "\n" ); document.write( "since x = sin(t), this means that sin(t) = 0.80901699437495 or sin(t) = -0.30901699437495\r
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\n" ); document.write( "\n" ); document.write( "when sin(t) = 0.80901699437495, your angle is either 54 degrees is 126 degrees.\r
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\n" ); document.write( "\n" ); document.write( "when sin(t) = -0.30901699437495, your angle is either 198 degrees or 342 degrees.\r
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\n" ); document.write( "\n" ); document.write( "your solution should therefore be either 54, 126, 198, or 342 degrees in the 0 to 360 degree interval.\r
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\n" ); document.write( "\n" ); document.write( "you would confirm by evaluating the original equation at each of those angles.\r
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\n" ); document.write( "\n" ); document.write( "if you do so, you will see that the original equation is true for all of them.\r
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\n" ); document.write( "\n" ); document.write( "therefore, your solution is 54, 126, 198, and 342 degrees in the 0 to 360 degree interval.\r
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\n" ); document.write( "\n" ); document.write( "this can be seen graphically as shown below:\r
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\n" ); document.write( "\n" ); document.write( "in this graph, you set up two equations.\r
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\n" ); document.write( "\n" ); document.write( "the first is y = 4 * cos^2(x) + 2 * sin(x)\r
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\n" ); document.write( "\n" ); document.write( "the secon is y = 3\r
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\n" ); document.write( "\n" ); document.write( "if the first equation is equal to the second equation, the graphs ill intersect and the intersection points will be as shown.\r
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