Differentiating Trigonometric Identities Cos z and Sin z for Complex z

Fortunately for students, the differentials of complex functions follow the same rules as for real functions, but for different reasons. In this video we show why d/dz (cos z) = - sin z and vice versa for complex 'z', with help from the hyperbolic functions sinh z and cosh z, as well as the Cauchy Riemann equations.
For more on calculus of complex numbers see our playlist 'Calculus of Complex Numbers' at • Calculus of Complex Nu...
For more practice with complex numbers see our playlist 'Complex Numbers' at • Complex Numbers

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For more on calculus of complex numbers see our playlist 'Calculus of Complex Numbers' at ua-cam.com/play/PLlX3COjsHPVC3950F2WhgxDR0-nyloONJ.html