Question

решите пожалуйста

$cos^{2}15*cos^{2}75$

Answer 1

Объяснение:

${cos}^{2} {15}^{0} \times {cos}^{2} {75}^{0} = {(cos {15}^{0} \times cos {75}^{0}) }^{2} = {( \frac{1}{2} \times (cos(15 - 75) - cos(15 + 75)) }^{2} =$

$= {( \frac{1}{2} \times (cos60 - cos90)) }^{2} = {( \frac{1}{2} \times ( \frac{1}{2} - 0)) }^{2} = {( \frac{1}{4})}^{2} = \frac{1}{16} = 0.0625$