Uzupełniona tabela:

α	30o	45o	60o
sinα	1/2	√2/2	√3/2
cosα	√3/2	√2/2	1/2
tgα	√3/3	1	√3

 

$\text{a)}\sin {45}^{\circ }+\cos {45}^{\circ }=\frac{\sqrt{2}}{2}+\frac{\sqrt{2}}{2}=\frac{{\sout{2}}^1\sqrt{2}}{{\sout{2}}^1}=\sqrt{2}$  

$\text{b)}\sin {30}^{\circ }\cdot \cos {60}^{\circ }+\sin {60}^{\circ }\cdot \cos {30}^{\circ }=\frac{1}{2}\cdot \frac{1}{2}+\frac{\sqrt{3}}{2}\cdot \frac{\sqrt{3}}{2}=\frac{1}{4}+\frac{3}{4}=\frac{4}{4}=1$  

$\text{c)}{\sin }^2{60}^{\circ }+{\cos }^2{60}^{\circ }={\left(\frac{\sqrt{3}}{2}\right)}^2+{\left(\frac{1}{2}\right)}^2=\frac{3}{4}+\frac{1}{4}=\frac{4}{4}=1$