In trigonometry, cos(x) represents the ratio between the length of the adjacent side to angle x in a right triangle and its hypotenuse.
Trigonometric Functions: Trigonometric functions are mathematical functions that relate angles to ratios of sides in right triangles.
Pythagorean Identity: The Pythagorean identity states that sin^2(x) + cos^2(x) = 1 for all real numbers x.
Radians: Radians are another way to measure angles using arc lengths along a unit circle rather than degrees.