Question

CALCULAȚI sin 30 DE GRADE COS DE60 DE GRADE - sin 60 degrade cos de 30 de grade

Answer 1

   
[tex]\displaystyle \\ \text{Rexolvare pentru scoala generala:}\\\\ \sin30^o\cos60^o - \sin60^o\cos30^o = \\\\ = \frac{1}{2}\times \frac{1}{2} - \frac{ \sqrt{3} }{2}\times \frac{ \sqrt{3} }{2}= \frac{1}{4}- \frac{3}{4}= -\frac{2}{4}=\boxed{-\frac{1}{2}}\\\\\\ \text{Rexolvare pentru liceu:}\\\\ \text{Folosim formula: } \sin a\cos b - \cos a \sin b= sin(a-b)\\\\ \text{Rezolvare:}\\\\ \sin30^o\cos60^o - \sin60^o\cos30^o =\\\\ =\sin(30^o - 60^0)= \sin(-30^o)=-\sin30^o = \boxed{-\frac{1}{2}}[/tex]