Question

triangle ABC is an abtuse triangle with the abtuse angle at vertex B. Angle A must be : less than 90 greater than 90. congruent to angle B congruent to angle C

Answer 1

If angle B of the triangle is obtuse, the two remaining angles, A and C, must both be acute--less than 90°. They are not necessarily congruent.

The 1st selection is the correct one: Angle A must be less than 90°.