Linked from
The 11 pages that link to Right angle, each with the reason it gives.
AngleBroader topic: It is the standard benchmark for classifying angles as acute or obtuse.
Degree (angle)Related: It provides a familiar benchmark equal to one quarter of a full turn.
Perpendicular bisectorBroader topic: It is the precise angle formed at the intersection.
RectangleRelated: Four right angles distinguish rectangles from most other quadrilaterals.
SquareRelated: Four right angles are part of the square’s defining conditions.
De Gua's theoremRelated: Three edges meeting at the distinguished vertex form pairwise right angles.