document.write( "Question 909017: Given the equation sin x = −0.2, find only the solutions that are in the interval [−π, 5π].
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document.write( "Round to nearest 0.01.\r
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document.write( "#confused. \r
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document.write( "Im plugged that into my calculator and gotten. x=-.20 in radians. However the interval part of the question is throwing me off. \n" );
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Algebra.Com's Answer #551480 by Theo(13342) You can put this solution on YOUR website! there are 4 quadrants in the interval from 0 to 2pi. \n" ); document.write( "first quadrant is 0 to pi/2 (same as 0 to 90 degrees) \n" ); document.write( "second quadrant is pi/2 to pi (same as 90 degrees to 180 degrees) \n" ); document.write( "third quadrant is pi to 3pi/2 (same as 180 to 270 degrees) \n" ); document.write( "fourth quadrant is 2pi(same as 270 to 360 degrees)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "once you get past 2pi, the cycle repeats itself.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your solutions will be in the interval of 0 to 2pi and then they will repeat themselves.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "let's do you problem and you'll see what i mean.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if you use your calculator to find the angle whose sine is -.2, the calculator will give you an angle of -.2013579208 radians.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that angle is in the fourth quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that doesn't really help you too much.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "it's better to find the angle in the first quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you do that by making the sine positive since all trig functions are positive in the first quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when you solve for sinx = .2, you get an angle of .2019579208 radians.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that becomes your reference angle.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you can use that angle to find all the other angles.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "now you know the sine is negative because that what you were given.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the sine is negative in quadrants 3 and 4.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the rules for finding an angle in each quadrant are as follows:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your reference angle is in quadrant 1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the rules for finding the angle in each quadrant are as follows:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the angle in quadrant 1 is the reference angle. \n" ); document.write( "the angle in quadrant 2 is pi minus the reference angle. \n" ); document.write( "the angle in quadrant 3 is pi plus the reference angle. \n" ); document.write( "the angle in quadrant 4 is 2pi minus the reference angle.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you want the angle in quadrant 3 and quadrant 4.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your angle in quadrant 1 is .2019579208 radians which is your reference angle.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your angle in quadrant 3 will be pi + .2019579208 radians = 3.342950574 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your angle in quadrant 4 will be 2pi - .2019579208 = 6.081827386 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your angle will be multiples of plus or minus 2pi radians until you get past the interval you are interested in.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the interval you are interested in is -pi radians to 5pi radians.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-pi radians is equal to -3.142592654 radians.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "5pi radians is equal to 15.70796327 radians.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your interval of interest is from -3.142592654 radians to 15.70796327 radians.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take your angle in quadrant 2 and keep adding 2*pi until you get past 15.70796327 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you will get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "3.342950574 + 1*2pi = 9.626135882 radians \n" ); document.write( "3.342950574 + 2*2pi = 15.90932119 radians ***** > 15.70796327 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take your angle in quadrant 2 and keep subtracting 2*pi radians until you get past -3.142592654 radians.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "3.342950574 - 1*2pi = -2.940234733 radians. \n" ); document.write( "3.342950574 - 2*2pi = -9.22342004 radians ***** < -3.142592654 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take your angle in quadrant 4 and do the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "6.081827386 + 1*2pi = 12.36501269 radians \n" ); document.write( "6.081827386 + 2*2pi = 18.648198 radians ***** > 15.70796327 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "6.081827386 - 1*2pi = -.2013579208 radians \n" ); document.write( "6.081827386 - 2*2pi = -6.484543228 radians ***** < -3.142592654 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your solutions are:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-2.940234733 radians \n" ); document.write( "-.2013579208 radians \n" ); document.write( "3.342950574 radians \n" ); document.write( "6.081827386 radians \n" ); document.write( "9.626135882 radians \n" ); document.write( "12.36501269 radians\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this will be easier to see on a graph. \n" ); document.write( "any difference in the numbers you see on the graph and the numbers shown above are due to rounding.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your graph will look like this:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |