Spherical Angle, is an angle formed by the intersection of two great circles of the sphere. All spherical angles are measured by an arch of a great circle described on the vertex as a pole, and intercepted between the legs which form the angle.
Angle lunular is an angle formed by the intersection of two curves, the one concave and the other convex.
Mixed-line Angle, is that comprehended between a right line and a curved line.
Curved-line Angle, is that intercepted between two curved lines meeting each other in one point, in the same plane.
Angle of a semi-circle is that which the diameter of a circle makes with the circumference.
Angle of Incidence, is that which the line of direction of a ray of light, &c. makes at the point where it first touches the body it strikes against, with a line erected perpendicular to the surface of that body.
Angle of interval between two places is that formed by two lines directed from the eye to those places.
Angle of Reflection, is the angle intercepted between the line of direction of a body rebounding, after it has struck against another body, and a perpendicular erected at the point of contact.
Angle at the centre, in fortification, is the angle formed at the middle of the polygon, by lines drawn from thence to the points of the two adjacent bastions.
| Angle of the curtain, | - | |
| Angle of the flank, |