Target angle submarine observer estimating target angle pictures himself on the target ship looking back at the submarine. Relative bearing of the submarine is the clockwise angle in degrees from the heading of the target ship to a straight line drawn from the target ship to the submarine. When target angle is 0° (or 360° ) the target ship is coming directly toward the submarine. Target angles between 0° and 90° indicate the target ship is moving toward and to the right of the submarine. Target angles between 90° and 180° indicate the target ship is moving to the right and away
Solid angle of its faces is one-sixth of that, or sr. Solid angles can also be measured in square degrees (1 sr = () square degrees), in square minutes and square seconds, or in fractions of the sphere (1 sr = fractional area), also known as spat (1 sp = 4 sr). In spherical coordinates there is a formula for the differential, where is the colatitude (angle from the North pole) and is the longitude. The solid angle for an arbitrary oriented surface S subtended at a point P is equal to the solid angle of the projection of the surface S