## MTALHAHASSAN2 one year ago Need help!! 8. Solve for theta. 0<theta<2pie. Given an exact answer, where possible. Otherwise, round to the nearest hundredth of a radians. 5 sin theta cos theta – 3 cos theta = 0

1. campbell_st

factor out cos $\cos(\theta)(5\sin(\theta) -3)$ now set each factor to zero and solve $\cos(tehta) = 0~~~and~~~5\sin(\theta) - 3 = 0$

2. MTALHAHASSAN2

|dw:1434604876572:dw|

3. MTALHAHASSAN2

can someone plz help me

4. MTALHAHASSAN2

@Michele_Laino

5. MTALHAHASSAN2

@KyanTheDoodle

6. MTALHAHASSAN2

@RezForLife

7. MTALHAHASSAN2

@Alexander95

8. MTALHAHASSAN2

@bleebleebleed

9. MTALHAHASSAN2

@Compassionate

10. MTALHAHASSAN2

@Data_LG2

11. MTALHAHASSAN2

@esam2

12. MTALHAHASSAN2

@freckles

13. anonymous

From your unit circle you can pick out where cosine is 0. For the sine solutions, you already have sin Θ = 0.6. Use the sin^-1 button on your calculator to find Θ Θ = sin^-1 (0.6) This gives an angle in the 1st quadrant. sine is also positive in the 2nd quadrant. Subtract the other solution from pi to get the angle in the 2nd quadrant. Θ = π - sin^-1 (0.6)

14. anonymous

do still need help i would have messaged u but i got blocked for god knows what

15. anonymous

@MTALHAHASSAN2

16. MTALHAHASSAN2

Θ = sin^-1 (0.6) i get 37 degree

17. anonymous

ican help or fleather me

18. MTALHAHASSAN2

@SkaterBoyShawn what is ur problem

19. MTALHAHASSAN2

I don't need ur help

20. MTALHAHASSAN2

@Michele_Laino

21. anonymous

i have no prob u said fleather me then blocked me i am confuesd make sense i dont know what i did to u

22. UsukiDoll

inb4 crazy ban from original poster ...stop mass tagging people.

23. MTALHAHASSAN2

@SkaterBoyShawn stop

24. anonymous

yes 37° is one solution. 180° - 37° = 143° is another solution

25. anonymous

now what did i do

26. MTALHAHASSAN2

wait but at the back the answer is different

27. MTALHAHASSAN2

it is something like 74

28. anonymous

stop tagging me iam bothing u so leave me alone bye have a good evning

29. Michele_Laino

we can factor out cos( \theta), so we can write: $\Large \cos \theta \left( {5\sin \theta - 3} \right) = 0$

30. campbell_st

you have missed on of the key aspects of the question, you are working in radians and you should have 4 angles as the solution

31. MTALHAHASSAN2

no@campbell

32. MTALHAHASSAN2

the answer is given in degrees

33. anonymous

@MTALHAHASSAN2 yes he's right. It is in radians

34. campbell_st

you solutions to the factor are correct.. $\cos(\theta) = 0$ what 2 angles measure make this true, remember its in radians...

35. anonymous

"0<theta<2pie" is what you typed above

36. MTALHAHASSAN2

oh yeah

37. MTALHAHASSAN2

38. campbell_st

the domain is given as $0 < \theta l< 2\pi$ so you should answer in radians

39. MTALHAHASSAN2

40. campbell_st

so the solutions for $\cos(\theta) = 0$ should be straight forward the 2 angles for $\sin(\theta) = \frac{3}{5}$ are in the 1st quadrant and 2nd quadrant

41. imqwerty

5sin(θ)cos(θ)-3cos(θ) = 0 divide by 5 sin(θ)cos(θ) -3/5cos(θ)=0 3/5=sin37(approx) sin(θ)cos(θ)-sin(37)cos(θ)=0 cos(θ)[sin(θ)-sin(37)]=0 either cos(θ)=0 i.e, (θ)=90 or sin(θ)-sin(37)=0 i.e (θ)=37 or 143 :)

42. campbell_st

does that make sense..?

43. MTALHAHASSAN2

so 37 and 143 be the answer

44. MTALHAHASSAN2

but i have to convert that in radians

45. campbell_st

so find the 1st quadrant angle for theta and then 2nd quadrant is $\pi - \theta$

46. campbell_st

this online calculator will do it for you http://web2.0calc.com/ just select radians

47. campbell_st

then input the ratio

48. MTALHAHASSAN2

how

49. campbell_st

select radian press 2nd... then asin which is arcsin $asin = \sin^{-1}$ then enter 0.6 and = what do you get?

50. campbell_st

oops should select Rad.. bottom left corner

51. MTALHAHASSAN2

ok

52. campbell_st

then 2nd asin (0.6) =

53. MTALHAHASSAN2

0.605

54. imqwerty

55. campbell_st

ummm not quite... I got 0.6435011.... can you just check again you have to press 2nd to before closing the brackets then =

56. MTALHAHASSAN2

i goted 0.64

57. campbell_st

great so that is the 1st quadrant answer to the nearest hundredth now the 2nd quadrant is $\pi - 0.64$

58. MTALHAHASSAN2

2.50

59. MTALHAHASSAN2

right

60. MTALHAHASSAN2

@campbell_st

61. campbell_st

yes.. that's it... well done

62. MTALHAHASSAN2

wait but at the back they have four solution

63. MTALHAHASSAN2

these two are the same but we are missing two

64. campbell_st

ok... so they are the values for sin now the values of cos you have $\cos(\theta) = 0$ what angles make it true..?

65. MTALHAHASSAN2

90

66. campbell_st

here is the curve |dw:1434608602050:dw|

67. campbell_st

68. MTALHAHASSAN2

pie/2

69. campbell_st

so where does the cos curve cut the horizontal axis..?

70. campbell_st

great, that's 1 and the other is..?

71. MTALHAHASSAN2

270 which is 3pie/2

72. campbell_st

that's correct... so you have 4 angles...

73. MTALHAHASSAN2

yes thanks a lot

74. campbell_st