sine

noun

\ˈsīn

Definition of sine

1 : the trigonometric function that for an acute angle is the ratio between the leg opposite the angle when it is considered part of a right triangle and the hypotenuse

2 : a trigonometric function sin θ that for all real numbers θ is exactly equal to the sine of an angle of measure θ in radians and that is given by the sum of the alternating series {latex}\sin \theta = \theta - \frac{\theta^{3}}{3!} + \frac{\theta^{5}}{5!} - \frac{\theta^{7}}{7!} + \frac{\theta^{9}}{9!} - \dots{/latex}

Examples of sine in a Sentence

Recent Examples on the Web

His sine law allows anyone with a decent grounding in trigonometry to use a pendulum to determine their latitude. — Alicia Ault, Smithsonian, "How Does Foucault’s Pendulum Prove the Earth Rotates?," 3 Feb. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'sine.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.