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Help me with this I don’t know if I need to use law of cosines or law of sines to find the degree

Help me with this I don’t know if I need to use law of cosines or law of sines to-example-1
User Taoufik J
by
7.9k points

1 Answer

4 votes

Answer:

Law of cosines

Explanation:

In this problem i need to use the law of cosines, because the angles are unknown.

we know that

The formula of the law of cosines is equal to


c^2=a^2+b^2-2(a)(b)cos(C)

where


a=7\ units\\b=8\ units\\c=10\ units\\C=\theta

substitute in the formula


10^2=7^2+8^2-2(7)(8)cos(\theta)


100=49+64-112cos(\theta)


100=113-112cos(\theta)


112cos(\theta)=113-100


112cos(\theta)=13


cos(\theta)=(13)/(112)

using a calculator


\theta=cos^-1((13)/(112))


\theta=83.33\°

User Rui Nunes
by
7.9k points

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