Dane:
a,b przyprostokatne,
c przeciwprostokatna
tga=4=\frac{4}{1}=\frac{a}{b}
a=4
b=1
c^2=a^2+b^2
c^2=16+1
c=\sqrt{17}
sina=\frac{a}{c}=\frac{4}{\sqrt{17}}*\frac{\sqrt{17}}{\sqrt{17}}=\frac{4\sqrt{17}}{17}
cosa=\frac{b}{c}=\frac{1}{\sqrt{17}}*\frac{\sqrt{17}}{\sqrt{17}}=\frac{\sqrt{17}}{17}
ctga=\frac{1}{tga}=\frac{1}{4}