Given up-pointing triangle△ABC, where a = 25, b = 20, and c = 30, find the measure of angle A.Round to the nearest degree.

To find the measure of angle A in triangle ABC, we can use the Law of Cosines. The Law of Cosines states that c² = a² + b² - 2ab*cos(C), where a, b, and c are the sides of the triangle and C is the angle we're trying to find. However, since we're trying to find angle A, we'll rearrange the formula to solve for cos(A):

cos(A) = (b² + c² - a²) / (2bc)

Substituting the given values:

cos(A) = (20² + 30² - 25²) / (22030) cos(A) = (400 + 900 - 625) / 1200 cos(A) = 675 / 1200 cos(A) = 0.5625

Now, to find the measure of angle A, we take the inverse cosine (or arccos) of 0.5625:

A = arccos(0.5625)

Using a calculator, we find that A ≈ 56 degrees when rounded to the nearest degree.