## Definition for AN'GLE

AN'GLE, n. [Fr. angle; L. angulus, a corner; Gr. αγκυλος, W. ongle; G. and D. angel, a hook, an angle; Dan. angel, a hook, angle, a sting; Sax. angel, a hook; Sp. and Port. angulo; It. angolo. The German has angeln, for angling to with a hook; but in D. hengel is the rod, and hengelen, to angle. Qu. hinge and hang.]

In popular language, the point where two lines meet or the meeting of two lines in a point; a corner. In geometry, the space comprised between two straight lines that meet in a point, or between two straight converging lines which, if extended, would meet; or the quantity by which two straight lines, departing from a point, diverge from each other. The point of meeting is the vertex of the angle, and the lines, containing the angle, are its sides or legs. In optics, the angle of incidence is the angle which a ray of light makes with a perpendicular to the surface, or to that point of the surface on which it falls. The angle of refraction is the angle which a ray of light refracted makes with the surface of the refracting medium; or rather with a perpendicular to that point of the surface on which it falls. – Encyc. A right angle is one formed by a right line falling on another perpendicularly, or an angle of 90 degrees, making the quarter of a circle. An obtuse angle is greater than a right angle, or more than 90 degrees. An acute angle is less than a right angle, or less than 90 degrees. A rectilineal or right-lined angle is formed by two right lines. A curvilineal angle is formed by two curved lines. A mixed angle is formed by a right line with a curved line. Adjacent or contiguous angles are such as have one leg common to both angles, and both together are equal to two right angles. External angles are angles of any right-lined figure without it, when the sides are produced or lengthened. Internal angles are those which are within any right-lined figure. Oblique angles are either acute or obtuse, in opposition to right angles. A solid angle is the meeting of three or more plane angles at one point. A spherical angle is one made by the meeting of two arches of great circles, which mutually cut one another on the surface of the globe or sphere. – Bailey.