Which term describes lines that intersect at a \( 90^{\circ} \) angle? A. Parallel B. Complementary C. Vertical D. Perpendicular

Did you know that the term "perpendicular" comes from the Latin word "perpendiculus," which means "to hang down"? This concept has been around since ancient times and is foundational in geometry, underlining the very principles used in architecture and design today. In real life, when you think about roads that cross each other at right angles, such as the intersection of a street grid, that's a perfect example of perpendicular lines at work. This concept appears everywhere—from the blueprints of buildings to the design of furniture, making it a critical aspect of both geometry and everyday life!