Definition of cotangent
1 : a trigonometric function that for an acute angle is the ratio between the leg adjacent to the angle when it is considered part of a right triangle and the leg opposite
2 : a trigonometric function cot θ that is equal to the cosine divided by the sine for all real numbers θ for which the sine is not equal to zero and is exactly equal to the cotangent of an angle of measure θ in radians
Origin of cotangent
New Latin cotangent-, cotangens, from co- + tangent-, tangens tangent
First Known Use: 1635
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