1. A= $2sin(3\pi-2x)+3cos(2x+\frac{13\pi}{2})+5tan(x-3\pi)-2sin^{2}(\frac{9\pi}{4}-x)-cos(-2x)$
2.B=$cot\frac{\pi}{18}.cot\frac{2\pi}{18}.cot\frac{3\pi}{18}...cot\frac{8\pi}{18}$
3. C=$4cos15^{o}.cos21^{o}.cos24^{o}-cos12^{o}-cos18^{o}$
4. D=$\frac{tan30^{o}+tan40^{o}+tan50^{o}+tan60^{o}}{cos20^{o}}$