Question

Fill in the blank with acute, obtuse, right, reflex or straight angle.

When one of the angles, which is less than a right angle is added to a right angle it forms a/an ____________ .

Answer 1

Any angle which is less than a right angle is an acute angle.

Now, let us take an angle less than a right angle (say $55°$)

According to the question,

$55°+90°=145°$

We know that, an angle greater than right angle and less than $180°$, is an obtuse angle.

Hence, when one of the angles, which is less than a right angle is added to a right angle it forms an obtuse angle.