Define a straight angle and write some examples of it.

If two lines intersect at a point, and if one pair of vertically opposite angles are obtuse angles, then the other pair of vertically opposite angles are _____.
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In the adjoining figure, name the acute vertically opposite angles

Sort the shapes based on the number of right angles they have:

Name the angle marked in the diagram.

The angle $x$ in the given figure is _____ angle. (Acute/Obtuse/Right/Straight)

In the adjoining figure, name the obtuse vertically opposite angles

Sort the shapes based on the number of right angles they have:

Name the angle marked in the diagram.

The angle $\left(x-2\right)°$ is an obtuse angle.

Two lines intersect at a point, and if one pair of vertically opposite angles are acute angles, then the other pair of vertically opposite angles are _____ angles.

How many acute angles can a right triangle have?

How many obtuse angles does a triangle have?