Calculate the cosine of any angle in degrees or radians with step-by-step working.
The cosine function returns the ratio of the adjacent side to the hypotenuse in a right triangle. For any angle θ, cos(θ) ranges from −1 to 1. cos(0°)=1, cos(90°)=0, cos(180°)=−1.
Cosine definition
cos θ = adjacent / hypotenuse
cos(60°) = 0.5. Standard values: cos(0°)=1, cos(30°)≈0.8660, cos(45°)≈0.7071, cos(60°)=0.5, cos(90°)=0.
They are complementary: sin(θ) = cos(90° − θ). Also, sin²θ + cos²θ = 1 for all θ (the Pythagorean identity).