Question

Решите уравнение 3-cos3x = 3cos²x+3sin²x

Answer 1

3 - cos (3x) = 3cos (x)² + 3sin (x)²

3 - cos (3x) = 3 (cos (x)² + sin (x)²)

3-cos (3x) = 3×1

3 - cos (3x) = 3

-cos (3x) = 0

cos (3x) = 0

3x = $\pi$/2 + k$\pi$, k є Z

x = $\pi$/6 + k$\pi$/3, k є Z