## tammyhawatmeh Group Title cos θ = − root2 /2 one year ago one year ago

1. baldymcgee6 Group Title

how can you get rid of the cosine?

2. tammyhawatmeh Group Title

arc cos?

3. baldymcgee6 Group Title

yep

4. baldymcgee6 Group Title

do you know the unit circle?

5. tammyhawatmeh Group Title

yup

6. baldymcgee6 Group Title

okay, so where is cos(θ) = -sqrt(2/2) ?

7. tammyhawatmeh Group Title

3pi/4

8. baldymcgee6 Group Title

Yes.. correct.

9. hartnn Group Title

10. hartnn Group Title

now do u need general solution or within the range 0 to 2pi ?

11. tammyhawatmeh Group Title

these are the directionsSolve the given equation. (Enter your answers as a comma-separated list. Let k be any integer. Round terms to two decimal places where appropriate.)

12. hartnn Group Title

means genearalized solution, can u generalize this ?

13. tammyhawatmeh Group Title

5pi/4 ,-5pi/4,3pi/4,-3pi/4

14. baldymcgee6 Group Title

There is an infinite amount of solutions, you need to write it in a way to GENERALIZE the solution.

15. hartnn Group Title

so let me generalize it. cos function is periodic with 2pi. so values repeat after every 2pi*k here, $$\theta =\pm(3\pi/4+2\pi k),\pm(5\pi/4+2\pi k)$$

16. tammyhawatmeh Group Title

ohh i see but why do u add the 2pik at the end ? because it is a periodic function?

17. hartnn Group Title

yes, as i said cos function is periodic with 2pi. so if a is solution, so is a+2pi, a-2pi,a+4pi,a-4pi, and so on

18. tammyhawatmeh Group Title

ohh i see i missed this whole lesson on this section and i dont know any of it