## anonymous 4 years ago when do i use sin, cos and tan in inverse form?

1. asnaseer

an example might be that you are told the sin of an angle is 0.5 and asked to find the angle. then you would use the inverse sin function.

2. asnaseer

does that help?

3. anonymous

so when looking for the sides of a triangle?

4. asnaseer

when looking for sides, you usually use the sin/cos/tan functions. the inverses are usually used to find the angles.

5. asnaseer

so you might be given an angle and one side, and asked to find another side - that involves using sin/cos/tan. on the other hand, you might be given 2 sides and asked to find the angle - that involves using the inverse functions.

6. anonymous

ohh ok... |dw:1327355865365:dw| how would i do this?

7. asnaseer

$\cos(60)=\frac{5}{x}$therefore:$x=\frac{5}{\cos(60)}$

8. anonymous

cosine is a/h?

9. asnaseer

yes

10. asnaseer

you can use the mneumonic SohCahToa to remember them. Soh ===> sin = o/h Cah ===> cos = a/h Toa ===> tan = o/a

11. asnaseer

you pronounce it as "SAW CAH TOE AH"

12. anonymous

when i have that e

13. anonymous

equation set up.. how do you solve for the x tho?

14. asnaseer

just work out the fraction - 5 divided by cosine of 60 degrees. I'm not sure where you are stuck?

15. anonymous

sry.. i thought it was 5/x tho?

16. asnaseer

ok - let me try to explain it step by step...

17. anonymous

thank you im horrible at math

18. asnaseer

ok, we know:$\cos(60)=\frac{5}{x}$are you happy with this statement?

19. anonymous

yes

20. asnaseer

good. so 1st step is to get rid of the 'x' in the fraction on the right hand side. the way you do that is to multiply both sides by 'x' as follows:$x*\cos(60)=x*\frac{5}{x}$

21. asnaseer

now, on the right hand side, the 'x' at the top and bottom of the fraction will cancel out to give you:$x*\cos(60)=\cancel{x}*\frac{5}{\cancel{x}}=5$

22. asnaseer

23. anonymous

yes!

24. asnaseer

ok, so next step we want to do is to leave just 'x' on the left hand side. that can be done by dividing both sides by $$\cos(60)$$ as follows:$\frac{x*\cos(60)}{\cos(6)}=\frac{5}{\cos(60)}$

25. asnaseer

then you'll notice the $$\cos(60)$$'s on the left hand side cancel each other out to give you:$\frac{x*\cancel{\cos(60)}}{\cancel{\cos(6)}}=\frac{5}{\cos(60)}$$x=\frac{5}{\cos(60)}$

26. asnaseer

make sense?

27. anonymous

yea.. for that would you get...-5.24?

28. asnaseer

$\cos(60)=0.5$so:$x=\frac{5}{\cos(60)}=\frac{5}{0.5}=10$

29. asnaseer

30. anonymous

yup :)

31. asnaseer

don't worry - we've all been there :)

32. anonymous

do u know how to find all sic trig functions...? lol

33. asnaseer

sic?

34. anonymous

six*

35. asnaseer

You might find this site useful: http://www.ping.be/~ping1339/gonio.htm

36. anonymous

okay

37. asnaseer

best thing to do is to keep practicing and post a question in this group when you get stuck on a particular problem. there are MANY people here who will be more than willing to spend time explaining things to you.

38. anonymous

okay thank you for helping

39. asnaseer

yw