which type of triangle must have perpendicular lines
Perpendicular The legs of a right triangle are perpendicular to each other.
Hermitian matrix The diagonal elements must be real, as they must be their own complex conjugate.
Bracket Forms include round (also called "parentheses"), square, curly (also called "braces"), and angle brackets (also called "chevrons"); and various other pairs of symbols.
Iambic pentameter As lines in iambic pentameter usually contain ten syllables, it is considered a form of decasyllabic verse.