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virtus

  • 3 years ago

In triangle ABC, CD bisects the angle BCA and D lies on side AB. Angle c = 60 degrees, AC = 8cm and BC = 6cm

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  1. virtus
    • 3 years ago
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    |dw:1342162593694:dw|

  2. virtus
    • 3 years ago
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    calculate the length of AB, giving your answer correct to one decimal place

  3. shandelman
    • 3 years ago
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    Are you allowed to use the law of cosines?

  4. dpaInc
    • 3 years ago
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    use the law of cosines.... \(\large (AB)^2=(AC)^2+(BC)^2-2(AC)(BC)cosC \)

  5. shandelman
    • 3 years ago
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    I'm not sure what DC has to do with anything...put there to confuse, I guess? I can't think of a better way to do solve it.

  6. virtus
    • 3 years ago
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    @dpaInc I tried to use cosine rule, but i don't think that is how you do it cause you get a whole no. as an answer and the question asks you to round off to 1 d.p Furthermore i checked the solution booklet and it says the answer is 7.2 cm

  7. shandelman
    • 3 years ago
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    ...I didn't get a whole answer, but I also didn't get 7.2. Hmm...

  8. shandelman
    • 3 years ago
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    Oh, wait. Hold on.

  9. shandelman
    • 3 years ago
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    No, I did get 7.2, never mind. c^2 = 6^2 + 8^2 - 2(6)(8)cos(60)

  10. virtus
    • 3 years ago
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    oh i must have made a mistake then! THANKS

  11. virtus
    • 3 years ago
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    I get 13.8 for some reason

  12. ganeshie8
    • 3 years ago
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    put the calculator in degrees measure.. .

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