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Derivatives of Trig Functions

We may often want to take derivatives involving the trigonometric functions. Rather than deriving them each time, it's much easier to simply remember the following derivatives.

Trig Derivatives

The derivatives of the six trigonometric functions are:

(sinx)=cosx          (cosx)=sinx(tanx)=sec2x      (secx)=secxtanx(cotx)=csc2x(cscx)=cscxcotx\begin{array}{c} \boxed{(\sin x)'=\cos x}\ \ \ \ \ \hspace{1 cm}\ \ \ \ \ \boxed{(\cos x)'=-\sin x } \\ \\ \boxed{(\tan x)'=\sec^{2} x} \ \ \ \ \ \ \qquad\boxed{(\sec x)'=\sec x\tan x} \\ \\ \boxed{ (\cot x)'=-\csc^{2}x}\qquad\boxed{(\csc x)'=-\csc x\cot x } \end{array}


Wize Tip
Notice how all the derivatives of "CO Functions" have a minus sign.

Wize Concept
The Product, Quotient, and Chain Rules still apply for Trig Derivatives!

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Example: Trig Derivatives


Find ddx(x2sinx)\displaystyle\frac{d}{dx}(x^2\sin{x}).

ddx(x2sinx)\displaystyle \frac{d}{dx}(x^2\sin{x})
=(ddxx2)×sinx+x2×(ddxsinx)\displaystyle =(\frac{d}{dx}x^2)\times\sin{x}+x^2\times(\frac{d}{dx}\sin{x})
=2xsinx+x2cosx\displaystyle =2x\sin{x}+x^2\cos{x}
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Example: Trig Derivatives

Find the derivative of f(x)=1+cosxxsinx\displaystyle f(x)=\frac{1+\cos x}{x-\sin x}


f(x)=y=1+cosxxsinx\displaystyle f(x)=y=\frac{1+\cos x}{x-\sin x}

Quotient rule:

y=sinx(xsinx)(1+cosx)(1cosx)(xsinx)2y'=\dfrac{-\sin x(x-\sin x)-(1+\cos x)(1-\cos x)}{(x-\sin x)^2}

=xsinx+sin2x1+cos2x(xsinx)2=\dfrac{-x\sin x+\sin ^2x-1+\cos ^2x}{(x-\sin x)^2}

=xsinx(xsinx)2=-\dfrac{x\sin x}{(x-\sin x)^2}
Find the derivative of

f(θ)=(sinθcosθ)secθ\displaystyle f(\theta)=(\sin\theta-\cos\theta)\sec\theta



Find y(23)y^{(23)} , the 23rd derivatives, given y=sinx\displaystyle y=\sin x.