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Graphing Trigonometry Equations

```
Date: 5/15/96 at 15:4:32
From: Anonymous
Subject: Graphing Trigonometry Equations

I am currently taking Mathematics 12 through correspondance, and I
haven't had very much trouble so far. But recently I came upon a
subject which the textbook barely covers. Here is an example that is
meant to be graphed:

Cos A Cos 3A - Sin A Sin 3A

This is equal to Cos (A + 3A) or Cos 4A.

But how do I graph this one:

Sin A - Cos A

Is there an identity that I am forgetting?  Thanks for your help.

Aaron S.
```

```
Date: 11/11/96 at 22:46:53
From: Doctor Robert
Subject: Re: Graphing Trigonometry Equations

I am not sure that I completely understand your question.  If you are
to graph y = sin x - cos x, you can make a table of values and plot
the graph without resorting to any identity to simplify it.  This
function can be very easily graphed on a graphing calculator.  If you
need to have the function in terms of only one trig function, you
could use the fact that

cos A = sqrt(1 - sin^2 A)

so that your function would be:

y = sin A - sqrt(1 - sin^2 A)

if that makes it any easier!

-Doctor Robert,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
```
Associated Topics:
High School Equations, Graphs, Translations
High School Trigonometry

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