Why is $\cos(\theta) < \dfrac{\sin(\theta)}{\theta}$ for $\theta \in (0,\dfrac{\pi}{2})$
60709
How do I get $\cos{\theta} \lt \frac{\sin{\theta}}{\theta} \lt 1$?
123490
L'Hopital's rule and $\frac{\sin x}x$
108223
If $\cos x=\cos y$ and $\sin x=\sin y$ is $x=y$ or $x=2\pi,y=0$ or $x=0,y=2\pi$? $x,y\in[0,2\pi]$
98741
Finding $\int_{0}^{\frac{\pi}{4}} \frac{\tan \theta - \tan^3 \theta}{\ln \tan \theta}$
60559
How prove this $x^3<\sin^2{x}\tan{x},x\in\left(0,\dfrac{\pi}{2}\right)$
31102
Why does $\frac{1}{r}\frac{dr}{d\theta} = \cot \psi$?
10289
Need help in proving that $\frac{\sin\theta - \cos\theta + 1}{\sin\theta + \cos\theta - 1} = \frac 1{\sec\theta - \tan\theta}$
35244
Prove $\sin^2\theta + \cos^2\theta = 1$
137060
Evaluating $\int_0^{\tfrac{\pi}{4}}\ln(\cos x-\sin x)\ln(\cos x) dx - \int_0^{\tfrac{\pi}{4}}\ln(\cos x+\sin x)\ln(\sin x)dx=\frac{G\ln 2}{2}$
5679
Why is $2\pi i \neq 0?$
88989
Why $x<\tan{x}$ while $0<x<\frac{\pi}{2}$?
91521
Ambiguity of notation: $\sin(x)^2$
156162
Are $\cos^2 \theta$ and $\cos \theta^2$ the same?
122395
Integrating $\sec\theta\tan^2\theta d\,\theta$
118884
The sine inequality $\frac2\pi x \le \sin x \le x$ for $0<x<\frac\pi2$
43184
Using the Residue Theorem to Prove that $\int^{2\pi}_{0} \frac{1}{(a+\cos\theta)^{2}} d \theta=\frac{2\pi a}{(a^{2}-1)^{3/{2}}}.$
11387
Mean Value Theorem: $\frac{2}{\pi}<\frac{\sin x}{x}<1$