document.write( "Question 1078505: If the graph of y=cos(pix)-2 is shifted up by 3 units, left by 1 unit and vertically stretched by a factor of 2, what will be new equation describing it?(explain too please)
\n" ); document.write( "a) y= 2cos(pi(x-1)) -5
\n" ); document.write( "b) y=cos(2pi(x-1)) +1
\n" ); document.write( "c) y=cos(2pix +1)-5
\n" ); document.write( "d) y=2 cos(pi(x+1))+1
\n" ); document.write( "e) none
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Algebra.Com's Answer #692940 by Theo(13342)\"\" \"About 
You can put this solution on YOUR website!
the general formula is:\r
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\n" ); document.write( "\n" ); document.write( "y = acos(b(x-c))+d\r
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\n" ); document.write( "\n" ); document.write( "a is the amplitude
\n" ); document.write( "b is the frequency
\n" ); document.write( "c is the horizontal shift
\n" ); document.write( "d is the vertical shift.\r
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\n" ); document.write( "\n" ); document.write( "your equation is y = cos(pi * x) - 2\r
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\n" ); document.write( "\n" ); document.write( "shift it up 3 units and it becomes y = cos(pi * x) + 1\r
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\n" ); document.write( "\n" ); document.write( "shift it to the left 1 unit and it becomes y = cos(pi * (x+1) + 1\r
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\n" ); document.write( "\n" ); document.write( "stretch it vertically by a factor of 2 and it becomes y = 2 * cos(pi * (x+1)) + 1\r
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\n" ); document.write( "\n" ); document.write( "my first graph is the original function.\r
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\n" ); document.write( "\n" ); document.write( "my second graph shifts the function from the first graph up by 3 units.\r
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\n" ); document.write( "\n" ); document.write( "my third graph shifts the function from the second graph to the left 1 unit.\r
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\n" ); document.write( "\n" ); document.write( "my fourth graph vertically expands the third graph by a factor of 2.\r
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\n" ); document.write( "\n" ); document.write( "the fourth graph is your solution.\r
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\n" ); document.write( "\n" ); document.write( "that looks like your selection d.\r
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\n" ); document.write( "\n" ); document.write( "note that:\r
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\n" ); document.write( "\n" ); document.write( "frequency is equal to 2pi / period.\r
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\n" ); document.write( "\n" ); document.write( "since the frequency of your first graph is pi radians, then the period is 2pi/pi = 2 radians.\r
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\n" ); document.write( "\n" ); document.write( "you get one complete cycle of the cosine wave in 2 radians as shown on the graph.\r
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\n" ); document.write( "\n" ); document.write( "in the first graph:\r
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\n" ); document.write( "\n" ); document.write( "the horizontal range goes from x = 0 to x = 2
\n" ); document.write( "the center line is y = -2
\n" ); document.write( "the vertical range goes from y = -1 to y = -3\r
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\n" ); document.write( "\n" ); document.write( "in the second graph:\r
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\n" ); document.write( "\n" ); document.write( "the horizontal range remains at x = 0 to x = 2
\n" ); document.write( "the center line moves up 3 units to y = 1
\n" ); document.write( "the vertical range becomes y = 2 to y = 0\r
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\n" ); document.write( "\n" ); document.write( "this is because the graph has been shifted up 3 units.\r
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\n" ); document.write( "\n" ); document.write( "in the third graph:\r
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\n" ); document.write( "\n" ); document.write( "the horizontal range becomes x = -1 to x = 1
\n" ); document.write( "the center line remains at y = 1
\n" ); document.write( "the vertical range remains at y = 2 to y = 0\r
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\n" ); document.write( "\n" ); document.write( "this is because the graph has been shifted to the left 1 unit.\r
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\n" ); document.write( "\n" ); document.write( "in the fourth graph:\r
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\n" ); document.write( "\n" ); document.write( "the horizontal range remains at x = -1 to x = 1
\n" ); document.write( "the center line remains at y = 1
\n" ); document.write( "the vertical range becomes y = 3 to y = -1\r
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\n" ); document.write( "\n" ); document.write( "this is because the vertical range has been multiplied by a factor of 2.\r
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\n" ); document.write( "\n" ); document.write( "here's a reference that looks pretty complete.\r
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\n" ); document.write( "\n" ); document.write( "http://www.mathguide.com/lessons2/GraphingTrig.html\r
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