Source TeX:

\begin{array}{cl} \cos^2(x) + \sin^2(x) = 1 &(1)\\1+\tan^2(x)=\sec^2(x) &(2)\\ \cot^2(x)+ 1 = \csc^2(x) &(3)\\ \cos(a+b)=\cos(a)\cos(b) - \sin(a)\sin(b) &(4)\\ \sin(a+b)=\sin(a)\cos(b) + \sin(b)\cos(a) &(5)\\ \cos(2a)=\cos^2(a) - \sin^2(a) &(6)\\ \sin(2a)=2\sin(a)\cos(a) &(7)\\ \cos^2(a) = \frac{1}{2}\Bigl(1 + \cos(2a)\Bigr) &(8)\\ \sin^2(a) = \frac{1}{2}\Bigl(1-\cos(2a)\Bigr) &(9)\\ \cos(-a) = \cos(a)&(10)\\ \sin(-a) = -\sin(a) &(11)\\ \cos(a)\cos(b)=\frac{1}{2}\Bigl(\cos(a-b) + \cos(a+b)\Bigr) &(12)\\ \sin(a)\sin(b)=\frac{1}{2}\Bigl(\cos(a-b) - \cos(a+b)\Bigr) &(13)\\ \sin(a)\cos(b)=\frac{1}{2}\Bigl(\sin(a-b) + \sin(a+b)\Bigr) &(14) \end{array}