Pre Calc

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In triangle ABC, b=14, c=15, and cos a= 3/5.

Find
a)side a
b) Sin B

Help please?

  • Pre Calc -

    In this notation, small letters are usually used to represent sides, and capital letters to indicate the angles at the vertex,
    so yours : b=14, c=15, cos A = 3/5

    direct application of the cosine law

    a^2 = 14^2 + 15^2 - 2(14)(15)cos A
    = ....

    once you have a
    use the Sine Law to find angle B

  • Pre Calc -

    ok. I have side A.
    How do you find angle B?

  • Pre Calc -

    sin B/b = sin A/a

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