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    http://www.mathsgenie.co.uk/resource...ne-areaans.pdf
    It's the last question
    Okay so I understood how they found the angle C, but then how did they use the cosine rule to find the missing side? I thought you could only use the cosine rule when you had an angle enclosed by 2 sides :confused:
    Thanks in advance
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    (Original post by sapphire79)
    http://www.mathsgenie.co.uk/resource...ne-areaans.pdf
    It's the last question
    Okay so I understood how they found the angle C, but then how did they use the cosine rule to find the missing side? I thought you could only use the cosine rule when you had an angle enclosed by 2 sides :confused:
    Thanks in advance
    u can rearrange it to get a^= b^2+c^2-2bcCosA to find the length of a missing side as well
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    (Original post by qwerty0301)
    u can rearrange it to get a^= b^2+c^2-2bcCosA to find the length of a missing side as well
    How is the missing side a when the side opposite the angle A is a?
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    (Original post by sapphire79)
    How is the missing side a when the side opposite the angle A is a?
    U can call any sides A,B or C but if u want u can also rearrange the equation to get:
    c^2= a^2+b^2-2abCosC or b^2= a^2+c^2-2acCosB

    I prefer doing that myself tbh
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    (Original post by qwerty0301)
    U can call any sides A,B or C but if u want u can also rearrange the equation to get:
    c^2= a^2+b^2-2abCosC or b^2= a^2+c^2-2acCosB

    I prefer doing that myself tbh
    Thanks
 
 
 
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