Question

Sa se calculeze $sin^2 130+cos^2 50$

Answer 1

 

$\displaystyle\bf\\Unghiul~de~130^o~este~in~cadranul~2.\\Il~aducem~pe~sin\,130^o~in~cadranul~1.\\\\sin\,130^o=sin\,(180^o-50^o)=sin\,50^o\\\\Folosim~formula:~~sin^2x+cos^2x=1\\\\sin^2130^o+cos^250^o=sin^250^o+cos^250^o=\boxed{\bf1}\\\\\implies~~\boxed{\bf~sin^2130^o+cos^250^o=1}$