Question

cos8x cos4x + sin8x sin4x=
$\frac{1}{2}$
​

Answer 1

Ответ:

x=±π/12+1/2πn, n∈Z

Объяснение:

cos8x cos4x + sin8x sin4x=1/2

cos(8x-4x)=1/2

cos4x=1/2

4x=+-pi/3+2pin

x=±π/12+1/2πn, n∈Z