# Thread: Solve Trig Equation for x

1. ## Solve Trig Equation for x

Solve the equation for 0 < x < 360°
sinx^2-1-cosx^2=0

I'm not sure how to factor it when there are two different variables.

2. ## re: Solve Trig Equation for x

Originally Posted by Braedong
Solve the equation for 0 < x < 360°
sinx^2-1-cosx^2=0
Is it $\displaystyle \sin(x^2)-1-\cos(x^2)=0$ OR is it $\displaystyle \sin^2(x)-1-\cos^2(x)=0~?~?$

3. ## re: Solve Trig Equation for x

Originally Posted by Braedong
Solve the equation for 0 < x < 360°
sinx^2-1-cosx^2=0

I'm not sure how to factor it when there are two different variables.
identities ... identities ... identities ...

$\displaystyle \sin^2{x} - (\sin^2{x} + \cos^2{x}) - \cos^2{x} = 0$

... did I mention something about identities ?

4. ## re: Solve Trig Equation for x

I haven't learned about identities yet, I have no idea what that is.

5. ## re: Solve Trig Equation for x

Originally Posted by Braedong
I haven't learned about identities yet, I have no idea what that is.
I cannot believe that you are at the point of solving trig equations and you have not encountered the basic Pythagorean identity $\displaystyle \sin^2{x} + \cos^2{x} = 1$ ...

is this an "online" course?

6. ## re: Solve Trig Equation for x

Originally Posted by Braedong
I haven't learned about identities yet, I have no idea what that is.
An identity is an equivalent expression. In this case, there are equivalent expressions that would simplify your equation greatly.

Second, you have not answered Plato's question in post #2. Until you do that, we can not help you any further.