Найдите приращение ∆x и ∆f в точке \(x_0 = \frac{2\pi}{3}\) , если f( \(x) = cos^2x\) и \(x = \frac{3\pi}{4} .\)

• \(\bigtriangleup x = \frac{\pi}{12}\)
• \(\bigtriangleup y = \frac{1 - \sqrt{2}}{2}\)
• \(\bigtriangleup y = \frac{1 + \sqrt{2}}{2}\)
• \(\bigtriangleup x = \frac{\pi}{4}\)