Definition of cosinus: Taylor series vs. right-triangle
87620
Different definitions of trigonometric functions
116270
Functional equations leading to sine and cosine
124897
How many ways are there to define sine and cosine?
36424
What is the Taylor series of $\ln \frac{1-x^2}{1+x^2}$?
152441
Vanishing of Taylor series coefficient
158703
Is series $\sum_{n=1}^{\infty}\frac{\cos(nx)}{n^\alpha}$, for $\alpha>0$, convergent?
5080
How can we sum up $\sin$ and $\cos$ series when the angles are in arithmetic progression?
123392
How does $cos(x) = \frac{\vec{v} \cdot \vec{w}}{|\vec{v}| \cdot |\vec{w}|}$ make sense?
124277
Taylor Series for $\log(x)$
119243
Taylor Series Expansion of $\frac{1}{\sin 2x}$ and $\frac{1}{1-e^{-x}}$
26678
The meaning of $\rightsquigarrow$ in math?
18967
Linear independence of $\sin(x)$ and $\cos(x)$
84846
Convergence of cos, sin, tan functions
82586
Why is cos -x equal to cos x?
80680
General term of Taylor Series of $\sin x$ centered at $\pi/4$
137607
Difference between left and right cosets
101838
Are Taylor series and power series the same "thing"?