The quarter section of a circle found by dividing the circle equally by two lines that meet at right angles at the centre,
In architecture and architectural mouldings, a quadrant is a convex curve with a 90º angle profile used to create form. As a moulding it is used to bridge gaps between two flat planes.
In furnishings, a quadrant is used as the first pattern section to cut circles for cushions, cloths and lampshades. First fold a square of fabric into four, then use the corner point as the centre of the circle and measure out the radii along the edges and at various points between to form an arc–effectively a quarter of the circle; draw, then cut along this arc, open up the fabric and there you have a full circle.