Lukecrayonz 2 years ago sin^2(x-1)/cos(-x)

1. Lukecrayonz

@amistre64

2. amistre64

might need to know alittle more about the question

3. Lukecrayonz

It just says to simplify @amistre64

4. amistre64

already seems "simple" to me :/

5. amistre64

you can try to shuffle some things about i spose; sin^2 = 1-cos^2 cos(a+b) = cosa cosb - sina sinb and stuff

6. amistre64

cos(-x) = cos(x) ... just some basic trig identities and properties that might be useful

7. Lukecrayonz

@amistre64 would you like the possible answers?

8. Lukecrayonz

Also quick question on another problem I'm stuck on.

9. amistre64

options would be able to narrow it down :)

10. Lukecrayonz

@amistre64 You there?

11. Lukecrayonz

@saifoo.khan

12. Lukecrayonz

A. -sinx B. cosx C. Sinx D. -cosx

13. saifoo.khan

Where are you stuck? @Lukecrayonz

14. Lukecrayonz

@saifoo.khan don't even know where to start :'(((

15. saifoo.khan

Use the 4th identity for numerator. http://www.a-levelmathstutor.com/images/trigonometry/ca-identities01.jpg

16. Lukecrayonz

The one Sin(A-B)?

17. saifoo.khan

Yep.

18. Lukecrayonz

How.. That makes no sense to me?

19. Lukecrayonz

If its sin^2 how would I use Sin(A-B)?

20. saifoo.khan

Ohhh. :o

21. Lukecrayonz

hmm?

22. Lukecrayonz

I think I got it

23. saifoo.khan

24. Lukecrayonz

sin^2x-1=-cos^2x cos(-x)=cosx so the answer is -cosx

25. saifoo.khan

Wait. How?

26. Lukecrayonz

-cos^2x/cosx=-cosx?

27. saifoo.khan

Step 1.

28. Lukecrayonz

cos(-x)=cosx

29. Lukecrayonz

Pythagorean identities sin^2x+cos^2x=1

30. saifoo.khan

$\frac{-\cos^2(x-1) +1}{\cos(-x)}$Then we should get this?

31. amistre64

shuffling trigs is a pain :)

32. saifoo.khan

No pain, no gain. ;)

33. amistre64

do you need to show work?

34. amistre64

http://www.wolframalpha.com/input/?i=simplify+sin%5E2%28x-1%29%2Fcos%28-x%29+ i dont see it popping out an option that you have