Which statement about longitude and latitude is true?

• A. Lines of longitude cross the Equator at right angles
• B. Lines of latitude cross the Equator at right angles
• C. Lines of longitude cross the poles at right angles
• D. Lines of latitude run north-south through the Equator

Answer: (A)

Longitude lines run north–south from pole to pole, while the equator is an east–west circle around the middle of the Earth. When a north–south line crosses that east–west circle, the angle is 90 degrees, so they meet at right angles. That’s why lines of longitude cross the equator at right angles.

Latitudes, on the other hand, run east–west and are parallel to the equator, so they don’t cross the equator (except the equator itself, which is the zero latitude). They intersect longitude lines, not cross the equator, which is why the statement about latitude lines crossing the equator at right angles isn’t true. At the poles, all longitudes meet, but that’s a special case and doesn’t change the perpendicular relationship at the equator.