daca abcd este romb=> m(∡bcd)= m(∡bad)
m(∡abc)=m(∡adc)
m(∡bcd)=2×(m∡acd)=>m(∡bcd)=2×15°=>m(∡bcd)=30°
m(∡bcd)= m(∡bad)=> m(∡bad)=30°
m(∡abc)+m(∡bcd)+m(∡cda)+m(∡dab)=360°
m(∡abc)+30°+m(∡cda)+30°=360°
dar m(∡abc)=m(∡cda)
2×m(∡abc)+60°=360°
m(∡abc)=(360°-60°):2
m(∡abc)=300°:2
m(∡abc)=150°...la restul nu inteleg ce ai scris.