Definition of cosine in English:



  • The trigonometric function that is equal to the ratio of the side adjacent to an acute angle (in a right-angled triangle) to the hypotenuse.

    • ‘If the two angles are the same we get the sines and cosines of double the angle.’
    • ‘In fact, it corresponds to the graph of a function called the hyperbolic cosine.’
    • ‘I can remember roughly how to differentiate a standard xy formula but sines, cosines and tangents are a mystery.’
    • ‘The optical path difference is directly proportional to the cosine of the angle of refraction through the coating.’
    • ‘Similar questions are investigated for the sine transforms rather than the cosine transforms.’