Graphs of Sine and Cosine

Easy Problem

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Graph the function f(x)=sinx-4

The subtraction of 4 has the effect of moving the parent function down 4 units.  Notice that the graph to the left has been moved down until the sinusoidal axis is located at -4.

Medium Problem

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Graph the function f(x)=sin(x+4)+7

The addition of 4 in the inside of the parenthesis moves the graph 4 units to the left.

The addition of 7 outside the parenthesis moves the graph up 7 units, making the sinusoidal axis at 7 instead of at 0.

Challenge Problem

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Graph the function f(x)=5sin2(x-2)+5

First, lets start with the 2 in front of the parenthesis.  To find the period of a sine graph, take the B value, which is 2, and divide 2π by it.  Therefore, the period of this graph is just π.

Next, lets take the 5 from the front.  This 5 increases the amplitude of the graph to 5, instead of 1.  Notice how the graph goes from a maximum of 10 (5 above the sinusoidal axis) to a minimum of 0 (5 below the sinusoidal axis).

Lastly, the 2 subtracted from inside the parenthesis moves the graph to the right 2 units.  And the addition of 5 outside the parenthesis moves the graph up 5 units, putting the sinusoidal axis at 5.




Real-World Example

Now that you know how to graph the sine function, try this real-world problem all by your self.

A dolphin follows the equation f(x)=3sin(x-2) after passing a certain point.  Graph 2 periods of the dolphin's path above and under the water.