Question

Якщо 7cos² a=1/3, то 7sin²a=?​

Answer 1

$\displaystyle\bf\\7Cos^{2} \alpha =\dfrac{1}{3} \\\\\\7\Big(1-Sin^{2} \alpha\Big )=\dfrac{1}{3} \\\\\\7-7Sin^{2}\alpha =\dfrac{1}{3} \\\\\\7Sin^{2} \alpha =7-\dfrac{1}{3} \\\\\\7Sin^{2}\alpha=6\dfrac{2}{3}$