To find the interior angle measure at vertex A using the inverse of cosine (also known as arccosine), you typically need the lengths of the sides of the triangle that includes angle A. The formula would generally look like this:
\[ \cos(A) = \frac{\text{adjacent side}}{\text{hypotenuse}} \]
or in the case of a triangle:
\[ \cos(A) = \frac{b^2 + c^2 - a^2}{2bc} \]
where \( a \), \( b \), and \( c \) are the lengths of the sides opposite to angles A, B, and C, respectively.
If you provide the lengths of the sides or any other relevant information, I can assist you in calculating the angle at vertex A and round it to the nearest whole degree.
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