Wartości funkcji trygonometrycznych dla kąta α
$\alpha \to$   $\text{f.tryg.}\downarrow$	$0^{\circ }$   $0$	${30}^{\circ }$ $\frac{\pi }{6}$	${45}^{\circ }$ $\frac{\pi }{4}$	${60}^{\circ }$ $\frac{\pi }{3}$	${90}^{\circ }$   $\frac{\pi }{2}$	${180}^{\circ }$ $\pi$	${270}^{\circ }$ $\frac{3\pi }{2}$	${360}^{\circ }$ $2\pi$
$\sin \alpha$	$0$	$\frac{1}{2}$	$\frac{\sqrt{2}}{2}$	$\frac{\sqrt{3}}{2}$	$1$	$0$	$-1$	$0$
$\cos \alpha$	$1$	$\frac{\sqrt{3}}{2}$	$\frac{\sqrt{2}}{2}$	$\frac{1}{2}$	$0$	$-1$	$0$	$1$
$\text{tg}\alpha$	$0$	$\frac{\sqrt{3}}{3}$	$1$	$\sqrt{3}$	nie istnieje	$0$	nie istnieje	$0$

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$\text{a) }5\cos {90}^{\circ }-8\sin {270}^{\circ }=5\cdot 0-8\cdot \left(-1\right)=8$  

$\text{b) }\sin {90}^{\circ }+\text{tg}{45}^{\circ }=1+1=2$  

$\text{c) }4\sin {90}^{\circ }-3\text{tg}{180}^{\circ }\cdot \sin {30}^{\circ }=4\cdot 1-3\cdot 0\cdot \frac{1}{2}=4$  

$\text{d) }7\cos \frac{\pi }{2}+4\text{tg}\pi =7\cdot 0+4\cdot 0=0$  

$\text{e) }\sin \frac{3}{2}\pi +\text{tg}\pi -6\sin \frac{\pi }{6}=-1+0-6\cdot \frac{1}{2}=-1-3=-4$  

$\text{f) }4\sin \pi -\cos \frac{\pi }{2}\cdot \sin \frac{\pi }{4}=4\cdot 0-0\cdot \frac{\sqrt{2}}{2}=0$