$\text{a)}$  

Z sumy miar kątów w trójkącie mamy:

$\alpha +\beta +\gamma ={180}^{\circ }$  

${17}^{\circ }+{30}^{\circ }+\gamma ={180}^{\circ }$  

${47}^{\circ }+\gamma ={180}^{\circ }$  

$\gamma ={180}^{\circ }-{47}^{\circ }$  

$\gamma ={133}^{\circ }$  

 

$\sin \gamma =\sin {133}^{\circ }=\sin \left({90}^{\circ }+{43}^{\circ }\right)=\cos {43}^{\circ }\approx 0,7314$    

$\cos \gamma =\cos {133}^{\circ }=\cos \left({90}^{\circ }+{43}^{\circ }\right)=-\sin {43}^{\circ }\approx -0,6820$   

$\mathrm{tg}\gamma =\mathrm{tg}{133}^{\circ }=\mathrm{tg}\left({180}^{\circ }-{47}^{\circ }\right)=-\mathrm{tg}{47}^{\circ }\approx -1,0724$  

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$\text{b)}$  

Z sumy miar kątów w trójkącie mamy:

$\alpha +\beta +\gamma ={180}^{\circ }$  

${28}^{\circ }+{45}^{\circ }+\gamma ={180}^{\circ }$  

${73}^{\circ }+\gamma ={180}^{\circ }$  

$\gamma ={180}^{\circ }-{73}^{\circ }$  

$\gamma ={107}^{\circ }$  

 

$\sin \gamma =\sin {107}^{\circ }=\sin \left({90}^{\circ }+{17}^{\circ }\right)=\cos {17}^{\circ }\approx 0,9563$   

$\cos \gamma =\cos {107}^{\circ }=\cos \left({90}^{\circ }+{17}^{\circ }\right)=-\sin {17}^{\circ }\approx -0,2924$   

$\mathrm{tg}\gamma =\mathrm{tg}{107}^{\circ }=\mathrm{tg}\left({180}^{\circ }-{73}^{\circ }\right)=-\mathrm{tg}{73}^{\circ }\approx -3,2709$