Calxsolver
Subject:  Trigonometry

Cosine

In a right triangle, the ratio of the side adjacent to an angle to the hypotenuse.

Cosine is the second primary trig function: cos θ = adjacent / hypotenuse. On the unit circle it is the x-coordinate after rotating θ radians from the positive x-axis. Sine and cosine are connected by sin²θ + cos²θ = 1.

Formula

cos θ = adjacent / hypotenuse

Used in

Trig Function Evaluator Evaluate sin, cos, tan, csc, sec or cot of an angle. Law of Cosines Solve a triangle from two sides and the included angle.

See also

Sine In a right triangle, the ratio of the side opposite an angle to the hypotenuse. Tangent (trig function) The ratio sin θ / cos θ — undefined when cos θ = 0.