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.

A. less than 90°

Step-by-step explanation:

An obtuse angle is an angle with a measurement greater than 90°. For this explanation, I'm going to give angle B the smallest obtuse measurement: 91°. The sum of the angle measures of any triangle has to equal 180. So, I'm going to subtract the obtuse angle from 180 to find the sum of the other two angles.

180 - 91 = 89

This means that, when added together, the angle measures of angle A and angle C equals 89°. Therefore, angle A (and C for that matter) has to be less than 90°, which means that your answer is A.

Hope this helps!

A. Less than 90

step-by-step explanation:

can someone answer this question plz

step-by-step explanation: