## rudra333 2 years ago arccos0?

1. tomo

1/cos(0)

2. rudra333

$\tan ^{-1}-\frac{ \sqrt{3} }{ 3}$

3. rudra333

@tomo is that the asnwer?

4. tomo

?? that doesn't make sense. please reword

5. rudra333

the one with tangent?

6. rudra333

what is arccos0??

7. tomo

cos(0) = 1.

8. rudra333

@tomo

9. Inspired

arccos(0)= 90 degrees or pi/2

10. tomo

one second. it is a little different than i first thought it was.

11. rudra333

k but plz try to expalin i have test on this toorrow

12. rudra333

k what is the answer of the questio with tangent?

13. rudra333

@Inspired

14. Inspired

Well it's just the inverse of cos(0). Cos(0) =1. The inverse of that switches the values of the sine cosine functions. cos(90) gives you 1. but because remember, sin(0)=0 and sin(90)=1

15. Inspired

cos(90) is 0*

16. Inspired

and an easy way to remember is: sin is your y axis and cos is your x axis. the inverse of a function is basically switches the x and y. what was y=f(x) is now x=f(y)

17. rudra333

k i know that but i have like 5 problems to work on i just want the right answers to it so i can practice

18. rudra333

for the test tomorrow

19. rudra333

socan u tell me the answer to the tangent one?plz

20. rudra333

$\arcsin-\frac{ \sqrt{3} }{ 2 }$

21. rudra333

and this one plz i have to go emergency plz answe those 2 for me plz

22. rudra333

23. Inspired

-pi/6 and -pi/3 (take a look at the unit circle for the second one)

24. fgoh

how did u get -pi/6? i know in the unit cirlce but when i tried all of them tan is y/x then which onw will work?

25. fgoh

@Inspired

26. Inspired

Let's see. arctan (sqrt3/3) is the same thing as arctan (1/sqrt3) right? and using 30-60-90 triangle, you have this: |dw:1358819026253:dw|

27. Inspired

Anyway, since the value is negative, it will occur in the 2nd or 4th Quadrant. Since we want a single value, you usually use the 4th quadrant, and that gives you a negative value.

28. fgoh

but is is y/x right why it doesn't work

29. fgoh

if u do it with the values on unit square and i thought the domain is from (pi/2,-pi/2)?

30. fgoh

|dw:1358819636475:dw|

31. fgoh

OMG K GET IT THANKS THANKS ALOT @Inspired U ARE AWESOME AND HELPFUL OMG THANKS THANKS I JUST FEEL SO HAPPY WHEN I GET IT THANKS

32. Inspired

:)

33. fgoh

$COS ^{-1}(\sin 11\pi/6)$

34. fgoh

@Inspired

35. fgoh

@Inspired last one

36. fgoh

and which one do u do first?

37. Inspired

ok :0 sin(11pi/6) is the same thing as sin(12pi/6-pi/6) so you get sin(2pi-pi/6) --> -sin(pi6)=-1/2 and so you have arccos(-1/2)

38. rudra333