Question

Triangle ABC is an obtuse triangle with the obtuse angle at the vertex B angle A must be?

Answer 1

Acute. No triangle can have more than 1 obtuse angle.

Answer 2

If B is obtuse, B > 90 degrees, then the remaining two angles add up to less than 90 degrees, so must be acute. In fact, at least one of A and C is less than 45 degrees, but we can't tell which.

Answer: A must be acute