Question

me ajudaaaa preciso com urgencia

Answer 1

$\sf sen \left( \alpha - \frac{\pi}{2} \right) \\ \\ \sf sen \left( \alpha - \frac{\pi}{2} \right) = sen \alpha .cos \frac{\pi}{2} - sen \frac{\pi}{2} .cos \alpha \\ \\ \sf sen \left( \alpha - \frac{\pi}{2} \right) = sen \alpha.cos90 {}^{ \circ} - sen90 {}^{ \circ}.cos \alpha \\ \\ \sf sen \left( \alpha - \frac{\pi}{2} \right) = sen \alpha .0 - 1.cos \alpha \\ \\ \boxed{\sf sen \left( \alpha - \frac{\pi}{2} \right) = - 1cos \alpha }$

$\sf sen \left( \alpha - \frac{\pi}{2} \right) = - 1cos \alpha \\ \\ \sf sen \left( \alpha - \frac{\pi}{2} \right) = - 1. \frac{1}{2} \\ \\ \boxed{\sf sen \left( \alpha - \frac{\pi}{2} \right) = - \frac{1}{2} }$