Question

solve : cos3x = cos2x​

Answer 1

$Cos3x = Cos2x$

$Cos3x - Cos2x = 0$

$-2Sin\frac{3x+2x}{2}Sin\frac{3x-2x}{2} = 0$

$Sin\frac{5x}{2}Sin\frac{x}{2} = 0$

$Sin\frac{5x}{2} = 0$    OR    $Sin\frac{x}{2} = 0$

$Sin\frac{5x}{2} = Sin(n\pi)$    OR    $Sin\frac{x}{2}= Sin(n\pi)$

$\frac{5x}{2} = n\pi$    OR    $\frac{x}{2}=n\pi$

HOPE THIS HELPS!!