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Life

  • 3 years ago

In triangle ABC, measure of angle A=33, a=12,b=15, what is the measure of angle b to the nearest degree?

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  1. Life
    • 3 years ago
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    @geoffb

  2. geoffb
    • 3 years ago
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    Are you given a diagram? You should be able to use sin, cos, or tan to find angle B, since you know two sides (a and b).

  3. geoffb
    • 3 years ago
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    |dw:1353915380080:dw|

  4. geoffb
    • 3 years ago
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    Does it look like that?

  5. geoffb
    • 3 years ago
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    If so, use a rule like \(\tan B = \frac{15}{12}\), though it might be different depending on your diagram.

  6. Life
    • 3 years ago
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    my diagram looks exactly like yours

  7. geoffb
    • 3 years ago
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    Perfect! You can solve for B using \(\tan^{-1} (\frac{15}{12})\) then.

  8. Life
    • 3 years ago
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    i got a long decimal, although the choices im giveb are all whole numbers

  9. geoffb
    • 3 years ago
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    Okay, wait... If the triangle was a right-angle triangle, you could have solved for B by simply subtracting 90-33. So I imagine that's not the case. It's not a right-angle triangle, I'm guessing.

  10. Life
    • 3 years ago
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    wait, dont i use the law of sine?

  11. geoffb
    • 3 years ago
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    Yes.

  12. Life
    • 3 years ago
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    idk man do you know why i keep getting the decimal, all im doing is putting in the inverse of tan(15/12) into my calculator

  13. geoffb
    • 3 years ago
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    No, forget I said that. That was for a right-angle triangle. Like you said, you need to use the law of sines. \(\Large\frac{a}{\sin A} = \frac{b}{\sin B}\) \(\Large\frac{12}{\sin 33} = \frac{15}{\sin B}\)

  14. geoffb
    • 3 years ago
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    \[\sin B = \frac{15 \sin 33}{12}\]

  15. geoffb
    • 3 years ago
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    Is 43 one of the possible answers?

  16. Life
    • 3 years ago
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    yea, so i dont find the inverse?

  17. geoffb
    • 3 years ago
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    Yes, you do. We got: \[\sin B = \frac{15 \sin 33}{12}\] so... \[B = \sin^{-1} (\frac{15 \sin 33}{12})\]

  18. Life
    • 3 years ago
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    I see now, thanks out :D

  19. geoffb
    • 3 years ago
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    No problem. Have a good night. :)

  20. Life
    • 3 years ago
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    same for you :)

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