The length of a is 13.68.
What is cosine law?
The law of cosines relates the lengths of the sides of a triangle to the cosine of one of its angles.
Using cosine theorem
AB² + AC² +2 AB* AC *cos A= a²
7*7 + 9*9 + 2* 7 * 7 cos 127 = a²
a²= 187.2028
a= 13.68
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