Math Formulas: Trigonometry Identities
www.mathportal.org › formulas › pdfDouble Angle and Half Angle Formulas 26. sin(2 ) = 2 sin cos 27. cos(2 ) = cos2 sin2 28. tan(2 ) = 2 tan 1 2tan 29. sin 2 = r 1 cos 2 30. cos 2 = r 1+cos 2 31. tan 2 = 1 cos sin = sin 1 cos 32. tan 2 = r 1+cos 1 cos Other Useful Trig Formulas Law of sines 33. sin = sin = sin Law of cosines 34. a2 = b2 +c2 2 b c cos b2 = a2 +c2 2 a c cos c2 = a2 ...
Trigonometric functions - Wikipedia
https://en.wikipedia.org/wiki/Trigonometric_functionsThe modern trend in mathematics is to build geometry from calculus rather than the converse. Therefore, except at a very elementary level, trigonometric functions are defined using the methods of calculus. Trigonometric functions are differentiable and analyticat every point where they are defined; that is, everywhere for the sine and the cosine, and, for the tangent…