# Trig identities (I think?) for precalc review

1. Sep 22, 2016

### Arnoldjavs3

1. The problem statement, all variables and given/known data
My calc class is having me review precalc(which i'm really rusty on...)

21. Find sin θ, sec θ, and cot θ if tan θ = 27
22. Find sin θ, cos θ, and sec θ if cot θ = 4.
23. Find cos 2θ if sin θ = 15
24. Find sin 2θ and cos 2θ if tan θ = √2
25. Find cos θ and tan θ if sin θ = 0.4 and π/2 ≤ θ < π.
26. Find cos θ and sin θ if tan θ = 4 and π ≤ θ < 3π/2.

2. Relevant equations

3. The attempt at a solution
I'm not going to ask you to do these for me, but since it's been several years since I've done any of this stuff(that i really do hate!) please refer me to videos / tutorials on how to work with them. My textbook only goes through one problem and that's it. The explanations are not the greatest as well.

Thanks alot. I apologize for not giving an attempt but all my attempts are so horribly off it's not even worth showing.

2. Sep 22, 2016

### Math_QED

3. Sep 22, 2016

### Staff: Mentor

This one makes no sense. $-1 \le \sin \theta \le 1$.

4. Sep 26, 2016

### Arnoldjavs3

It was meant to be sinx = 1/5. I've solved all the original question, they were a bit easier than I had imagined.

Should I still post the solutions or can I mark this question as solved and move on?

5. Sep 26, 2016

### SammyS

Staff Emeritus
Probably either is fine. See what others say.

Was #21 supposed to have 2/7 rather than 27?

6. Sep 29, 2016

### Arnoldjavs3

Yeah, it was 2/7. Not sure why they turned the way they did when I had copy pasted them