The spherical law of sines is a formula used in spherical geometry, which deals with figures on the surface of a sphere. It relates the sides and angles of a spherical triangle, stating that the ratio of the length of a side to the sine of its opposite angle is constant for all three sides and angles. This law is particularly useful in navigation and astronomy. In a spherical triangle, if the sides are denoted as a, b, and c, and the opposite angles as A, B, and C, the spherical law of sines can be expressed as: sin(a)/sin(A) = sin(b)/sin(B) = sin(c)/sin(C). This relationship helps in solving for unknown sides or angles when given sufficient information about the triangle.