Question

помагите срочно решить 10 номер а,б,в

Answer 1

$1) frac{sin2a}{sina} = frac{2sinacosa}{sina} =2cosa \ \ 2) cos2a+sin^2a=cos^2a-sin^2a+sin^2a=cos^2a \ \ 3) frac{2sinbcosb}{cosb} -sinb= frac{2sinbcosb-sinbcosb}{cosb} = frac{sinbcosb}{cosb} =sinb \ \ 4) frac{cos^2a-sin^2a}{cosa+sina} - frac{cos^2a+sinacosa}{cosa+sina} = frac{cos^2a-sin^2a-cos^2a-sinacosa}{cosa+sina} = \ \ = frac{-sina(sina+cosa)}{cosa+sina} =-sina$