Parallel lines are lines that never cross each other - they keep the same distance apart from each other. When two lines intersect, the opposite (X) angles are equal. On parallel lines, alternate (Z) ...

Parallel lines close parallel lines Lines which never meet and stay the same distance apart. Parallel lines are indicated by a pair of arrows. are two or more straight lines that remain the same ...

Summary We prove the next generalization of the Steiner-Lehmus theorem: if two equal cevians intersect with each other on the angle bisector of the third triangle vertex, then the triangle is ...