triangle abc is an obtuse triangle with the obtuse angle at vertex b. angle a must be less than 90°. greater…

triangle abc is an obtuse triangle with the obtuse angle at vertex b. angle a must be less than 90°. greater than 90°. congruent to angle b. congruent to angle c.

triangle abc is an obtuse triangle with the obtuse angle at vertex b. angle a must be less than 90°. greater than 90°. congruent to angle b. congruent to angle c.

Answer

Brief Explanations:

An obtuse - angled triangle has one angle greater than 90°. In triangle ABC, angle B is obtuse (greater than 90°). The sum of the interior angles of a triangle is 180°. So, the sum of angles A and C must be less than 90° (since angle B>90°). Thus, each of angles A and C must be less than 90°.

Answer:

less than 90°.