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Solution
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Solution provided by AtoZmath.com
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Law of Cosines calculator
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 1. Find Side a using Side b = 7, Side c = 8, Angle A = 60
2. Find Side b using Side a = 7, Side c = 8, Angle B = 60
3. Find Side c using Side a = 7, Side b = 8, Angle C = 60
4. Find Angle A using Side a = 3, Side b = 4, Side c = 5
5. Find Angle B using Side a = 3, Side b = 4, Side c = 5
6. Find Angle C using Side a = 3, Side b = 4, Side c = 5
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Example1. Find Side a using Side b=7, Side c=8, Angle A=60 (Law of Cosines)
Solution:
We have `b=7,c=8,A=60`
The law of cosines states that
`a^2=b^2+c^2-2 b c * cos(A)`
`:.a^2=7^2+8^2-2*7*8*cos(60)`
`:.a^2=49+64-2*7*8*0.5`
`:.a^2=49+64-56`
`:.a^2=57`
`:.a=sqrt(57)`
`:.a=7.5498`
Perimeter `P=b+c+a=7+8+7.5498=22.5498`
Area `=1/2 bc*sin(A)=1/2 *7*8*sin(60)=1/2 *7*8*0.866=24.2487` |
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