Find m∠a given δabc where a=4, b=6, c=3.

For this question, we're going to use the law of cosines.
The law of cosines is the following equation:



We know the values of a, b, and c. We want to find the measure of angle A.




Now, plug in these values into the equation.




Add both sides by  and subtract both sides by 16



Divide both sides by 36



Take the inverse cosine, or arc cosine, of both sides.
Using a calculator, you'll get the following result.



The measure of angle A should be 36.3 degrees. Hope this helps! :)