## SugarRainbow 3 years ago how would you find ^3square root of 38 if you know how I would put that on a calculator that's fine too

1. miteshchvm

do you have a scienrific calculator?

2. sauravshakya

|dw:1347856598297:dw|

3. sauravshakya

Type it on calculator

4. SugarRainbow

5. SugarRainbow

i gots 3.36

6. SugarRainbow

just so everyone absolutely knows the problem looks like this |dw:1347856966969:dw|

7. sauravshakya

Yes thats it

8. SugarRainbow

o kay now how would you find the value of the expression : if sin beta=0.45, find cos(pi/2-beta)

9. miteshchvm

its the same

10. SugarRainbow

okay then i did it right, what bout if tan(pi/2-beta)=-5.32, find cot beta

11. hartnn

tan(pi/2-beta)= cot beta = -5.32

12. SugarRainbow

okay cool then I think i got it so if sin (beta-pi/2)=0.73, to find cos-beta i would do cos(sin^-1-pi/2) right? or cos^-1(sin^-1-pi/2)

13. hartnn

remember these identities: $$sin(\pi/2-\beta)=cos\beta \\ tan(\pi/2-\beta)=cot\beta \\ cos(\pi/2-\beta)=sin\beta$$ when the ratio has angle $$\pi/2 - \beta$$ , it becomes coratio.

14. SugarRainbow

so is it the same if its beta-pi/2 instead of pi/2-beta?

15. hartnn

no, its only for pi/2-beta for beta-pi/2, u write it as -(pi/2-beta) and use sin(-x)=-sin x cos(-x)=cos x tan(-x)=-tan x

16. SugarRainbow

okay so to do if sin (beta-pi/2)=0.73, find cos-beta it would be cos(-pi/2-sin^-1(0.73)?

17. hartnn

there is no need to do $$sin^{-1}$$here. $$sin(\beta-\pi/2)=sin(-(\pi/2-\beta))=-sin(\pi/2-\beta)=-cos\beta$$

18. SugarRainbow

so then how would i do the problem?

19. hartnn

so cos beta =- sin (beta-pi/2)= -0.73

20. SugarRainbow

oh well IDK how i did it but I got that answer too. okay so last one of these is if cot(-beta)=7.89, find tan( beta-pi/2) would it kinda be like the previous one?

21. hartnn

yes. use tan(beta-pi/2) = tan(-(pi/2-beta))=??

22. SugarRainbow

23. SugarRainbow

0.03? wait I think i did it wrong let me try again

24. SugarRainbow

um okay one last try

25. SugarRainbow

1.20?

26. hartnn

ok, from where are u getting those numbers ?? tan(beta-pi/2) = tan(-(pi/2-beta))=-tan(pi/2-beta)=-cot beta and cot(-beta)=-cot beta also so tan(beta-pi/2) = cot(-beta) =7.89 see whether u understand this ?

27. SugarRainbow

well idk what i put for beta i tried it as just 7.89 and cot(7.89) here i'll try it again

28. SugarRainbow

well i understand how it works but idk how to put it into my calc to where i get that answer