## dessyk Group Title need help im going to draw a triangle and im doing the law of sines so if anyone can help please do cuz im confused.. please click this to helpp 2 years ago 2 years ago

1. dessyk Group Title

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2. GT Group Title

Do you need to find a?

3. dessyk Group Title

so let me explain im trying to find a okay c=96.3, b=145.67 , B=39.5degrees, C=74.2degrees,

4. dessyk Group Title

law of sines is a/sinA=b/sinB

5. GT Group Title

Sine rule says: SinA/a = SinB/b = SinC/c

6. dessyk Group Title

okay i understand that waitt why is it sina/a instead of a/sin a

7. GT Group Title

SinA/a = Sin(39.5)/145.67 SinA = a*something

8. GT Group Title

Because they mean the same thing. A/B = C/D => B/A = D/C

9. dessyk Group Title

waitt does it even matter

10. dessyk Group Title

okay im not understanding

11. GT Group Title

You can find angle A by simply subtracting angles B and C from 180.

12. dessyk Group Title

okay i understand which would be 66.8

13. GT Group Title

Then, use this: SinA/a = Sin(39.5)/145.67 SinA = a*something SinA/something = a To find a.

14. GT Group Title

SinA/a = SinB/b = SinC/c IS SAME AS a/SinA = b/SinB = c/SinC

15. dessyk Group Title

but then a would be .00436

16. GT Group Title

I am getting 210.5

17. GT Group Title

That "something" in my expression is 0.00436. Divide Sin66.8 by that "something" value. Then, you get the value of a.

18. dessyk Group Title

really then let me try again...... im still not getting that are you multiplying or dividing

19. GT Group Title

SinA/a = Sin(39.5)/145.67 SinA = a*0.00436 a = SinA/0.00436 a = Sin66.8/0.00436 a = 210.5

20. dessyk Group Title

im not getting it first you divided than you did something else im so confused

21. dessyk Group Title

ok

22. dessyk Group Title

23. GT Group Title

Post it separately.

24. dessyk Group Title

i dont understand

25. imagreencat Group Title

26. dessyk Group Title

okay, so instead of 66.8 its 66.3

27. dessyk Group Title

im so fustrated im confusedd

28. GT Group Title

Punch it into the calculator and you get slightly different number from 210.5

29. GT Group Title

SinA/a = Sin(39.5)/145.67 SinA = a*0.00436 a = SinA/0.00436 a = Sin66.3/0.00436 a = 210

30. dessyk Group Title

i neeed helpppp

31. dessyk Group Title

i got -47.99

32. imagreencat Group Title

Check your calculator first. I'm guessing you're getting different answers because your calculator is not in degree mode. That's why it's treating your angles differently.

33. dessyk Group Title

wait no i got -110.05

34. GT Group Title

How in the world can a length of a side of a triangle be negative? Can you show the arithmetic you used to get that number?

35. dessyk Group Title

yeppp m ycalculator wasnt in degree mode so let me try again

36. dessyk Group Title

yayy i got 209.69

37. GT Group Title

Good....close enough to 210. :)

38. dessyk Group Title

next problem b=58.2 c=68.3 C=51.3 degrees were gunna find a

39. GT Group Title

At this point, it is simply plugging in values into that sine rule ratios and cranking out numbers in a calculator. There is not much help you need.

40. dessyk Group Title

yeaa but i want to do it my self then have someone do it so i can nn check my answer to make sure its correct

41. dessyk Group Title

i got 7105. 88

42. dessyk Group Title

43. GT Group Title

It can't be that big.

44. GT Group Title

Angles are almost close to each other. So, side lengths have to be close to each other too.

45. dessyk Group Title

well i must be doing something wrong but sin68.3/51.3=.018111746

46. dessyk Group Title

128.7/.018111746=7105.88

47. GT Group Title

b=58.2 c=68.3 C=51.3 degrees SinB/b = SinC/c => SinB = 58.2 * Sin(51.3)/68.3 => SinB = 0.665 B = 41.68

48. dessyk Group Title

becuase i couldnt find A or B so i figured they were the same by suntracting 180-51.3

49. dessyk Group Title

ohhh ok so u must follow the formula

50. GT Group Title

Now that you know B, you find A by doing 180 - 51.3 - 41.68 = 87

51. dessyk Group Title

noww i get it

52. GT Group Title

SinA/a = SinC/c => a = c * SinA/SinC => a = 68.3 * Sin(87)/Sin(51.3) => a = 87.4

53. dessyk Group Title

ok

54. wombat Group Title

@dessyk The following variations of Law of Sines are the same: $\frac{a}{\sin(A)} = \frac{b}{\sin(B)}=\frac{c}{\sin(C)}$ and $\frac{\sin(A)}{a}=\frac{\sin(B)}{b}=\frac{\sin(C)}{c}$

55. GT Group Title

He got that. :)

56. wombat Group Title

ok :)

57. dessyk Group Title

hello

58. GT Group Title

yeah

59. dessyk Group Title

i have another question but hoew did you get 41. sometrhing but i got 45.42

60. GT Group Title

You mean for B = 41? I did the inverse sine function on the value 0.665.

61. dessyk Group Title

yes, ohh reallyy you see im confused now i thought u just i thought u just took .6650*68.3=45.42

62. GT Group Title

Sin(B) = 0.665 => B = inverse sine (0.665). On the calculator, you have to first press 0.665. Then, inv button, then the sin button.

63. GT Group Title

That gives you angle B.

64. dessyk Group Title

i didnt get that

65. jatinbansalhot Group Title

dessyk.. nice drawing.. :) :)

66. dessyk Group Title

thank you i guesss lol can yoiu help me!!

67. jatinbansalhot Group Title

what is the question

68. dessyk Group Title

its up above next problem b=58.2 c=68.3 C=51.3 degrees were gunna find a

69. dessyk Group Title

law of sines

70. jatinbansalhot Group Title

i didn't see above but u can find it very easily.. the formula is sin a / a = sin b / b = sin c / c or a /sin a = b / sin b = c / sin c use any of them what caters ur problem

71. dessyk Group Title

okay but when i tried i started to get fustrated because i wasnt getting the righ tanswer

72. jatinbansalhot Group Title

did my answer help u even a bit or not ?

73. dessyk Group Title

a little bit its just that i need help going through the process

74. petewe Group Title

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75. petewe Group Title

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76. petewe Group Title

get it?