Triangle ABC is an obtuse triangle, meaning the largest angle of the triangle is obtuse. This angle is located at vertex B, leaving the remaining two angles of the triangle to be acute. Knowing this, we can determine the measurement of angle A.

## Obtuse Triangle ABC

A triangle is classified as an obtuse triangle when one of the angles is greater than 90 degrees. In triangle ABC, the obtuse angle is located at vertex B, which is the largest angle of the triangle. This leaves the remaining two angles of the triangle, angles A and C, to be acute angles.

## Angle A Measurement

Since triangle ABC is an obtuse triangle, we can calculate the measurement of angle A. We know that the sum of the interior angles of any triangle is 180 degrees, and since vertex B is the obtuse angle, it must measure greater than 90 degrees. Therefore, angle A must measure less than 90 degrees, and when combined with angle C, the two angles must add up to 180 degrees. Therefore, the measurement of angle A is determined by subtracting the measure of angle C from 180 degrees.

In conclusion, triangle ABC is an obtuse triangle with the obtuse angle located at vertex B. Knowing this, we can determine the measurement of angle A by subtracting the measure of angle C from 180 degrees.

A triangle ABC is a three-sided figure in which three angles meet at the three vertices, A, B, and C. Triangle ABC is an obtuse triangle, meaning it has one angle that is greater than 90 degrees. In this particular triangle, the obtuse angle falls at vertex B. By definition, an obtuse triangle has one angle that is greater than the sum of the other two angles. Therefore, angle A must be less than 90 degrees, as the three angles in any triangle always total 180 degrees.

Given the information provided, we can determine that angle A must be less than 90 degrees. This can be proven using the Law of Cosines, which states that the square of the longest side of a triangle (the side opposite the obtuse angle) is equal to the sum of the squares of the other two sides, minus twice their product multiplied by the cosine of the included angle. In this case, if we let the longest side of triangle ABC be a, then we can calculate:

a2 = b2 + c2 – 2bc * cos(A)

Therefore, angle A falls between 90 degrees and 0 degrees. If a triangle is obtuse, then its sides must not be the same length and it must have one angle greater than 90 degrees. In triangle ABC, this angle is at vertex B and angle A is less than 90 degrees.