An angle less than 90 degree is called

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An angle less than 90 degree is called. . . . . .

An angle less than 90 degrees is called an acute angle.

To determine whether an angle is acute, you can use a protractor or rely on the properties of specific geometric shapes. Here's how:

1. Using a Protractor: Place the protractor on a flat surface with its center point aligned with the vertex of the angle. Then, align one of the protractor's arms with one side of the angle. Read the measurement marked on the protractor where the other side of the angle crosses. If the measurement is less than 90 degrees, the angle is acute.

2. Triangle Angles: In a triangle, if all three angles measure less than 90 degrees, then all the angles are acute.

3. Right Triangle: If one angle in a triangle measures exactly 90 degrees, the other two angles must be acute.

4. Quadrilateral Angles: In a quadrilateral, if all four angles measure less than 90 degrees, then all the angles are acute.

Remember, an acute angle is always less than 90 degrees.