## How Can We Draw The Graphs Of Trigonometric Functions?

December 3rd, 2006 . by VanajaWe have four ways to alter the graph of a function: vertical translation, vertical scaling, horizontal translation, and horizontal scaling. Note that some or all four of these can be applied to a function at once in the sense that you may have to deal with a function of the form y = AsinB(x - C) + D. You should simply work these graphs out one step at a time, concerning yourself first with the affect of B and C, then the affect of the presence of A, and finally the affect of D.

**Example:**

Draw the graph of y =2 sin(x/2+?/6)+3

**Solution**Let’s change this is of the form y = AsinB(x - C) + D

So y =2 sin(x/2+?/6)+3

can be written as y =2 sin ½ [x-(-?/3)]+3

Step 1: Draw sinx

B= ½ .so period is 4pi. That means it completes one cycle after 4pi.so stretch the graph horizontally so that its period is 4pi.

Next, we see that C=-pi/3. This will horizontally shift our graph pi/3units to the left. Thus, we now have

Now A=2, which will vertically scale our graph by a factor of 2. Thus, at this point, our range should now be [-2,2]

Finally, we must shift our graph vertically 3 units due to the presence of D=3. Hence, our range will now move to [1,5]

We can adopt the same method for drawing the graphs of other trigonometric functions. But remember first you should convert the given functions of the form

y = A sinB(*x* - C) + D

y = A cosB(*x* - C) + D

y = A tanB(*x* - C) + D

or accordingly, depending upon which of the trigonometric function is given.