## ZeroAT Group Title Please tell me how to do this problem Evaluate : sin(1/4 pie) A) 1 B) 0 C) sqrt 2 /2 D None of these 3 years ago 3 years ago

1. abhisheksingh59 Group Title

C) sqrt 2 /2

2. ZeroAT Group Title

How did u get this?

3. satellite73 Group Title

look at the unit circle on the last page of this cheat sheet.

4. cyter Group Title

c

5. satellite73 Group Title

you will see that at $\frac{\pi}{4}$ both the first and second coordinate on the unit circle is $\frac{\sqrt{2}}{2}$ so both sine and cosine are the same there

6. satellite73 Group Title

you can also do it directly using a triangle but this one comes up so often it is best to memorize it

7. ZeroAT Group Title

ok then how would i do a problem like tan( -337 pie /4 )

8. satellite73 Group Title

oh lord. first of all you best find a point between 0 and 2 pi that is coterminal with $\frac{-337\pi}{4}$

9. myininaya Group Title

pie?

10. satellite73 Group Title

myininaya will who you how, because last time i did this i got in a huge discussion mmmm pie

11. myininaya Group Title

apple pie?

12. ZeroAT Group Title

o.o

13. myininaya Group Title

chicken pot pie

14. satellite73 Group Title

ok fine. lets to it the easy (for me) way $\frac{-337}{4}=-84\tfrac{1}{4}$ and since 2 divides 84 evenly this angle is co terminal with $-\frac{\pi}{4}$

15. satellite73 Group Title

rhubarb pie

16. myininaya Group Title

what value does pie hold?

17. myininaya Group Title

does pie=pi?

18. satellite73 Group Title

$\sin(-\frac{\pi}{4})=-\frac{\sqrt{2}}{2}, \cos(-\frac{\pi}{4})=\frac{\sqrt{2}}{2}$ and since tangent is the ratio of sine over cosine you get -1

19. ZeroAT Group Title

so the final answer is -1?

20. satellite73 Group Title

yup

21. satellite73 Group Title

and if you doubt me, here is proof http://www.wolframalpha.com/input/?i=tan%28-337+pi%2F4%29

22. satellite73 Group Title

$\color{blue}{\text{sk}}\color{red}{\pi}\color{blue}{\text{y}}$

23. satellite73 Group Title

that, my myininaya, was for you

24. myininaya Group Title

pie?

25. satellite73 Group Title

c'mon. what did i write?

26. myininaya Group Title

pi?

27. satellite73 Group Title

nope

28. satellite73 Group Title

what do you see there?

29. myininaya Group Title

lol this pie concerns me

30. myininaya Group Title