Verified Answer :

x^2=(7^2)+(16^2)-2(7)(16)cos31
x^2=49+256-2(112)cos31
x^2=305-2(112)cos31
x^2=112.99
x=10.62

Hope that helps!! :)

law of cosines:
a²=b²+c²-2bc(cos A)

In this case:
x=x
b=16
c=7
A=31º

Therefore:
a²=b²+c²-2bc(cos A)
a²=16²+7²-2(16)(7)(cos 31º)
a²=256+49-192
a²=113
a=√113
a≈10.63

Answer: x≈10.63

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