Terminal Sides

[Vavin07]

Find the values of SinΘ , CosΘ , and TanΘ for an angle in standard position with (-3,20) on its terminal side.

Im confused on whether you use r^2= √ -3^2+√ 20^2 which is Undefined or r^2=√ -3^2+20^2 which is r=n=4√391 ?

 

[MarkFL]

Hello, and welcome to FMH!

I would let:

[MATH]r=\sqrt{x^2+y^2}=\sqrt{(-3)^2+(20)^2}=\sqrt{409}[/MATH]
And then:

[MATH]\sin(\theta)=\frac{y}{r}[/MATH]
[MATH]\cos(\theta)=\frac{x}{r}[/MATH]
[MATH]\tan(\theta)=\frac{y}{x}[/MATH]