Question

Daca sin 40° = t , exprimati in functie de t valoarea sin 140°. Aratati ca sin² 137° + cos² 43° = 1

Answer 1

   
[tex]1) \\ sin~40^o = t \\ sin~140^o = sin(180^o-140^o) = sin~40^o = \boxed{t} \\ \\ 2) \\ sin^{^2}137^o +cos^{^2}43^o = \\ = sin^{^2}(180^o-137^o) +cos^{^2}43^o = sin^{^2}(43^o) +cos^{^2}43^o = \boxed{1}[/tex]