Differentiation of $\sin x$ using Pythagoras theorem:
25569
Intuitive understanding of the derivatives of $\sin x$ and $\cos x$
91251
$n$th derivative of $e^{ax}\sin(bx+c)$
46642
Continuity of $\sin(x)/x$
104427
Sines and cosines of angles in arithmetic progression
133880
$|\sin^2x-\sin^2y|\le K|x-y|$ find K
157918
Finding the derivative of $x^x$
153816
Real Roots and Differentiation
28096
Finding the derivative of $x\uparrow\uparrow n$
118687
Prove an inequality with a $\sin$ function: $\sin(x) > \frac2\pi x$ for $0<x<\frac\pi2$
36741
Anti-derivative of continuous function $\frac{1}{2+\sin x}$
33396
Generalizing a Trig Identity
74409
Differentiaion Calculus: Trig Inverse Function.
137844
Proof of $\sin nx=2^{n-1}\prod_{k=0}^{n-1} \sin\left( x + \frac{k\pi}{n} \right)$
43956
Differentiating $f(x)^{g(x)}$
103487
Integration of the cardinal sine
99918
The $100$th derivative of $(x^2 + 1)/(x^3 - x)$
12726
Differentiating both sides of a non-differential equation