posted by Louis

I'm in gr 11 doing Trigonometry

14.2 = b
---- ----
sin38 sin 67

a = 46
--- ----
sin20 sin130

(10.7)^2 = (9.5)^2 + (12.4)^2 - 2(9.5)(12.4) cos <B

I just need someone to explain this to me because I just don't get it... thank you for any help

  1. bobpursley

    You are dealing with the law of sines and cosines. I am not certain what you don't get. Is it the algebra?

    1) b=14.2*sin67 / sin38 put these in the calculator and compute.

    2) Same issue:
    a= 46*sin20/sin130

    3) Law of cosines:
    cosB= ((10.7)^2 - (9.5)^ - (12.4)^2 )/[(9.5)(12.4)]

    Then to find angle B, take the inverse cosine of that result.

    If you have questions, ask.

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