Trigonometry deals with relationships between angles and sides of triangles. Cosine function relates adjacent side to hypotenuse in right triangles. Cosine of angle A equals hypotenuse length divided by adjacent side length
Arccos is the inverse cosine function for x between -1 and 1. Arccos(x) = cos-1(x) is the inverse cosine equation. Arccos and cosine can cancel each other in the domain [-1,1]
Vector direction is measured as angle between positive x-axis and vector. Vector tail is at origin, tip at (X, Y) coordinate. Vector can point in any direction from 0 to 360 degrees
A 3-4-5 triangle is a right-angled triangle with side lengths in 3:4:5 ratio. The triangle's perimeter is 12 units and its area is 6 square units. The sides are legs (3 and 4 units) and hypotenuse (5 units)
A right triangle has one 90° angle and two complementary acute angles. The total internal angles of a triangle is 180°. The sum of complementary angles equals 90°
Arcsin is the inverse of sine function. Returns angle whose sine is given number. Inverse functions have same name with 'arc' prefix. Example: arcsin 0.5 = 30°