Learn how to use sine, cosine and tangent functions to find angles and distances in right-angled triangles and other triangles. See examples, graphs, calculators and links to more topics on trigonometry.
While sine and cosine are readily identifiable as the projections of the radius on the vertical and horizontal axis, we need to see the definition of the tangent to understand how to find it and visualize it: \tan (\alpha) = \frac {\sin (\alpha)} {\cos (\alpha)} tan(α) = cos(α)sin(α)
Sin is the ratio of the opposite side to the hypotenuse, cos is the ratio of the adjacent side to the hypotenuse, and tan is the ratio of the opposite side to the adjacent side. They are often written as sin (x), cos (x), and tan (x), where x is an angle in radians or degrees. Created by Sal Khan.
Learn the basic and Pythagorean identities for trigonometric functions, such as sin, cos, tan, cot, sec and csc. Find out how to use them to simplify expressions, calculate angles and solve equations. See examples, formulas and diagrams.
Basic Identities: tan( tan( cot( sin( ) ) = cos( ) ) = cot( ) ) = tan( ) cot( sec( csc( Pythagorean Identities cos2( ) + sin2( ) = 1 sec2( ) − tan2( ) = 1 ) ) cos( = sin( ) ) = 1 cos( ) ) = sin( ) csc2( ) − cot2( ) = 1 Double Angle Identities sin(2 ) = 2 sin( ) cos( ) cos(2 ) = 1 − 2 sin2( ) cos(2 ) = 2 cos2( ) − 1 cos(2 tan(2
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sin cos tan rules
