Triangular arch

In architecture, a triangular arch typically defines an arch where the intrados consists of two straight segments formed by two stone slabs leaning against each other. In this roof-like arrangement, mitre joint is usually used at the crown, thus the arch was in the past also called a mitre arch. Brick builders would call triangular any arch with straight inclined sides. Mayan corbel arches are also sometimes called triangular due to their shape.
Since the sides of a triangular arch are experiencing bending stress, it is a false arch in a structural sense. The design was used in Anglo-Saxon England until the late 11th century over small openings.