Mastering Angles: Definitions, Measurements, And Applications

Angles

Determined by rotating a ray (half-line) about its endpoints

1. What is an angle?
An angle is the measured amount of rotation between two intersecting lines.

2. How is an angle measured?
Angles are usually measured in degrees. A degree is a unit of measurement that represents 1/360th of a full rotation.

3. What is a straight angle?
A straight angle is an angle that measures exactly 180 degrees. It is a straight line.

4. What is a right angle?
A right angle is an angle that measures exactly 90 degrees. It forms the corner of a square or rectangle.

5. What is an acute angle?
An acute angle is an angle that measures less than 90 degrees.

6. What is an obtuse angle?
An obtuse angle is an angle that measures more than 90 degrees but less than 180 degrees.

7. How do you use a protractor to measure an angle?
The protractor is placed on the vertex of the angle and the two arms of the angle are aligned with the markings on the protractor. The measurement is then read off the protractor where the second arm of the angle intersects.

8. What is a complementary angle?
Two angles are complementary if their sum is 90 degrees. For example, 30 degrees and 60 degrees are complementary angles.

9. What is a supplementary angle?
Two angles are supplementary if their sum is 180 degrees. For example, 110 degrees and 70 degrees are supplementary angles.

10. What is an adjacent angle?
Two angles are adjacent if they share a common vertex and a common side, but have no common interior points. For example, a square has four adjacent angles in each corner.

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