Learn how to calculate the cosine of an angle using the cos theta formula, which is the ratio of the adjacent side to the hypotenuse of a right triangle. Find the values of cos theta for different angles and see how it is used in various fields and problems. Trigonometric Identities You might like to read about Trigonometry first! Right Triangle The Trigonometric Identities are equations that are true for Right Angled Triangles. (If it isn't a Right Angled Triangle use the Triangle Identities page) Each side of a right triangle has a name: What is the relation among all the trigonometrical ratios of (90° - θ)? In trigonometrical ratios of angles (90° - θ) we will find the relation between all six trigonometrical ratios. The fundamental cos theta formula that you use for calculating the cosine is cosθ = base/hypotenuse Here, The base is known to be the base of the triangle, while the hypotenuse is the side opposite to the right angle of the triangle. If θ is one of the acute angles of the triangle, then sinθ is the ratio of the opposite side of the hypotenuse, and the cosec is the ratio of the adjacent side to the hypotenuse. The cosine directly relates to the right-angle triangle, and the calculation of ...
