1.
ABC triunghi dreptunghic⇒ m(∡A)=90°
In ΔABC avem:
m(∡A)+m(∡B)+m(∡C)=180°⇔
⇔90°+30°+m(∡C)=180°⇔
⇔120°+m(∡C)=180°⇔
⇔m(∡C)=180°-120°⇔
⇔m(∡C)=60°
Masura celui de-al doilea unghi este de 60°.
2)
x/2=y/3=z/5=k
x/2=k⇔
⇔x=2k
y/3=k⇔
⇔y=3k
z/5=k⇔
⇔5k
x+y+z=180⇔
⇔2k+3k+5k=180⇔
⇔10k=180⇔
⇔k=180/10⇔
⇔k=18
x=2k⇔
⇔x=2×18⇔
⇔x=36
y=3k⇔
⇔y=3×18⇔
⇔y=54
z=5k⇔
⇔z=5×18⇔
⇔z=90
Unghiurile au masura de 36°,54° respectiv 90°.