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? asked in Science & MathematicsMathematics · 6 years ago

maths help trig gcse?

Need help. I think I got answer, wasn't neat tho

My answer was 5.31

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3 Answers

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  • Anonymous
    6 years ago

    This is gcse??? Im 25 and I cant comprehend anything im seeing!

  • Wayne DeguMan
    Lv 7
    6 years ago

    Considering triangle ADB and using the 'sine rule' we get:

    x/sin55 = 7.4/sin80

    => x = 7.4sin55/sin80

    so, x = 6.16 cm

    Therefore, AC => 6.16 + 5.8 = 11.96 cm

    Now, considering triangle ABC and using the 'cosine rule' we get:

    a² = 7.4² + 11.96² - 2(7.4)(11.96)cos45

    so, a² = 197.8016 - 177.008cos45

    => a² = 72.64

    i.e. a = 8.5 cm

    :)>

  • MojoMaj
    Lv 6
    6 years ago

    Using the Law of Cosines is correct.

    Source(s): https://www.mathsisfun.com/algebra/trig-cosine-law...
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