if a triangle has the sides a=412, b=324, c=636, what is the measure of angle A?
we can choose from these answers:
e) none of these
1. According to the Cosine rule an angle greater than 90° must be opposite the largest side in the triangle. That is the side c and not the side a, which is opposite the angle at A.
2. You probably have forgotten about the negative sign in the denominator and therefore the correct result would be:
180° - 145.5202602° = 34.479...°