# Thread: Solving a trig equation.

1. ## Solving a trig equation.

Find the maximum(minus) answer of this equation:

(sinx-2)(cosx+ $\displaystyle \frac{\sqrt{3}}{2}$ )=0

Is it -$\displaystyle 30^0$?

Thanks.

2. sinx-2 is never zero.

so you left with:

cosx=-sqrt(3)/2)

can you find the solutions for that?

3. Originally Posted by Ellla
Find the maximum(minus) answer of this equation:

(sinx-2)(cosx+ $\displaystyle \frac{\sqrt{3}}{2}$ )=0

Is it -$\displaystyle 30^0$?

Thanks.
There is a minimum at -30 degrees, yes.
However, there are also solutions to f(x)=0.

Are you looking for the graph minimum or solutions to f(x)=0 ?

4. Originally Posted by Also sprach Zarathustra
sinx-2 is never zero.

so you left with:

cosx=-sqrt(3)/2)

can you find the solutions for that?
x = $\displaystyle \frac{\pi}{6}$ +2$\displaystyle \pi$ k...and what should I do next?

Well, the answer is degrees and I am looking for maximum not min. Thank you.

5. Originally Posted by Ellla

Well, the answer is degrees and I am looking for maximum not min. Thank you.
You did mention a "negative maximum",
so are you looking for a point on the graph furthest below the x-axis?
Also, if you are looking for a maximum of any kind,
solving f(x) = 0 doesn't find it.

The most negative value is a minimum.

6. Originally Posted by Archie Meade
You did mention a "negative maximum",
so are you looking for a point on the graph furthest below the x-axis?
Also, if you are looking for a maximum of any kind,
solving f(x) = 0 doesn't find it.

The most negative value is a minimum.
Yes, sorry for not explaining properly what I was looking for.

so are you looking for a point on the graph furthest below the x-axis?
Yes.

7. Are you attempting a solution using differentiation or by other means ?

8. Originally Posted by Archie Meade
Are you attempting a solution using differentiation or by other means ?
This, If I have any problems I will let you know