Right angle Right angle In geometry and trigonometry, a right angle is an angle of exactly 90° (degrees), corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles. The term is a calque of Latin "angulus rectus"; here "rectus" means "upright", referring to the vertical perpendicular to a horizontal base line. Closely related and important geometrical concepts are perpendicular lines, meaning lines that form right angles at their point of intersection, and orthogonality, which is the property of forming right angles, usually applied
Less-than sign encoded as a single-byte code point token. In Fortran, operator .LE. means "less than or equal to". In Bourne shell and Windows PowerShell, the operator -le means "less than or equal to". In the R programming language, the less-than sign is used in conjunction with a hyphen-minus to create an arrow (codice_1), this can be used as the left assignment operator. In Bourne shell (and many other shells), less-than sign is used to redirect input from a file. Less-than plus ampersand (<&) is used to redirect from a file descriptor. Less-than sign is used in the spaceship operator. In HTML