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Math Help - [SOLVED] trignometery law of cosines

  1. #1
    ramisha
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    [SOLVED] trignometery law of cosines

    in triangle , p=5 cm, q=7cm and angle R=60 degrees. find r.
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  2. #2
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    Hello, ramisha!

    In triangle: p=5 cm, q=7 cm and \angle R=60^o . Find r.

    This is a straight-forward application of the Law of Cosines: . r^2\;=\;p^2 + q^2 - 2pq\cos R

    We have: . r^2 \:=\:5^2 + 7^2 - 2(5)(7)\cos60^o

    Can you finish it?

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