Răspuns :
La primul punct am aplicat teorema lui Pitagora, sper sa te ajute!
(30, 40, 50) - triplet pitagoreic ⇒ AC = 30
[tex]\it sinB=\dfrac{AC}{BC}=\dfrac{^{2)}30}{\ 50}=\dfrac{60}{100}=0,6\\ \\ \\ cosB=\dfrac{AB}{BC}=\dfrac{^{2)}40}{\ 50}=\dfrac{80}{100}=0,8\\ \\ \\ tgB=\dfrac{AC}{AB}=\dfrac{^{25)}30}{\ \ 40}=\dfrac{750}{1000}=0,75[/tex]