FTCE General Knowledge Math Practice Test

What do you call angles that are opposite each other when two lines intersect?

1. Complementary angles

2. Supplementary angles

3. Adjacent angles

4. Vertical angles

The correct answer is: Vertical angles

The correct term for angles that are opposite each other when two lines intersect is vertical angles. When two lines cross, they form pairs of angles that are located directly across from one another. These angles are always equal in measure. This characteristic of vertical angles is fundamental in geometry, making them an important concept. For instance, if two lines intersect and one angle measures 70 degrees, the angle directly opposite it will also measure 70 degrees. This relationship is useful in solving various geometric problems and proofs. Thus, identifying vertical angles correctly is essential for understanding the properties of intersecting lines.