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pythagoras123

  • one year ago

In a triangle ABC, the ratios of the sides are such that a:b:c = 2:3:4. Calculate the value of cos C and hence find the value of sin C.

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  1. triciaal
    • one year ago
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    |dw:1441947104976:dw|

  2. triciaal
    • one year ago
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    |dw:1441947280594:dw|

  3. pythagoras123
    • one year ago
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    uh could you show how you calculate sin C using the above formulas

  4. pythagoras123
    • one year ago
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    @triciaal

  5. triciaal
    • one year ago
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    given only the 3 sides of the triangle first use the cosine rule to find the largest angle ( the one opposite the longest side) then you can use the sine rule to find the other 2 angles. Here we only need to find the sin of c we already calculated C you just use the calculator to find sin C.

  6. pythagoras123
    • one year ago
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    oh my question requires it to be in exact form

  7. pythagoras123
    • one year ago
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    is there a way to find sin C without the calculator

  8. triciaal
    • one year ago
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    @jim_thompson5910 @ganeshie8 can we use the ratio of the sides of the triangle as the lengths of each side?

  9. triciaal
    • one year ago
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    @pythagoras123 use the Sin rule above

  10. triciaal
    • one year ago
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    @Nnesha @zepdrix what would be the lengths of the sides for this triangle?

  11. pythagoras123
    • one year ago
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    @triciaal we don't know any of the values for sin A, sin B or sin C

  12. triciaal
    • one year ago
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    not until after we find the largest angle. you need to read the responses more carefully.

  13. triciaal
    • one year ago
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    |dw:1441948484416:dw|

  14. triciaal
    • one year ago
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    |dw:1441948763123:dw|

  15. pythagoras123
    • one year ago
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    I get that but how do we use the value of cos C to find the value of sin C without solving for the angle C itself?

  16. triciaal
    • one year ago
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    think about your username any ideas?

  17. pythagoras123
    • one year ago
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    oh I get it now lol thx

  18. triciaal
    • one year ago
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    |dw:1441949293293:dw|

  19. pythagoras123
    • one year ago
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    so with just the ratios of the sides given, we can find the trig ratio?

  20. triciaal
    • one year ago
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    |dw:1441949484079:dw|

  21. pythagoras123
    • one year ago
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    ok thx for your help :)

  22. triciaal
    • one year ago
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    cosine rule C is the largest angle

  23. triciaal
    • one year ago
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    you are welcome

  24. triciaal
    • one year ago
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    @zepdrix thanks

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