Question

sina-sinB если a=165° и B=75​​​

Answer 1

Ответ:

$\sin( \alpha ) - \sin( \beta ) = \sin(165^{\circ}) - \sin(75^{\circ}) = \\ = 2 \sin( \frac{165^{\circ} - 75^{\circ}}{2} ) \cos( \frac{165^{\circ} + 75^{\circ}}{2} ) = \\ = 2 \sin(45^{\circ}) \cos(120^{\circ}) = 2 \times \frac{ \sqrt{2} }{2} \times ( - \frac{1}{2} ) = - \frac{ \sqrt{2} }{2}$