Help with maths question Watch

username2899906
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#21
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#21
(Original post by Incarcarus)
1/2 a b sin (c) = area

c = sin-1 (10.5 / 1/2*4*7)
c = 48

Using a^2=b^2+c^2-2bc cos(A)
the final side length turns out to be 5.2 which cannot be correct
This is 100% the same as the one in the exam question https://imgur.com/a/Tv4I3Mt so should be correct.
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meggie16
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#22
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#22
(Original post by Incarcarus)
1/2 a b sin (c) = area

c = sin-1 (10.5 / 1/2*4*7)
c = 48

Using a^2=b^2+c^2-2bc cos(A)
the final side length turns out to be 5.2 which cannot be correct
This is not correct because we know that the angle x is the largest. Therefore, you can do 180-48.59 = 131.41. Using this to find the opposite side will give you 10.1cm, which makes more sense as it is the longest side.
Therefore, tan(x) = -1.13
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Incarcarus
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#23
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#23
(Original post by meggie16)
This is not correct because we know that the angle x is the largest. Therefore, you can do 180-48.59 = 131.41. Using this to find the opposite side will give you 10.1cm, which makes more sense as it is the longest side.
Therefore, tan(x) = -1.13
Yes, thank you, I was incorrect
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_mialouise01
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#24
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#24
1/2(7)(4)sinx=10.5
1/2(28)sinx=10.5
sinx=10.5/14
x=sin^-1(3/4)
x=48.59 degrees

therefore tan(48.59)=1.13 or 1.1 what you got.
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username2899906
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#25
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#25
(Original post by meggie16)
This is not correct because we know that the angle x is the largest. Therefore, you can do 180-48.59 = 131.41. Using this to find the opposite side will give you 10.1cm, which makes more sense as it is the longest side.
Therefore, tan(x) = -1.13
Thank you!

I actually got it correct! It just doesn't seem like it would be the correct answer.
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meggie16
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#26
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#26
(Original post by Goldfish4343)
Thank you!

I actually got it correct! It just doesn't seem like it would be the correct answer.
Np mark schemes tend to be wrong a lot haha
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