Y = sinx x cosx + cosx x sinx carilah turunan fungsinya dan nilai dari x = 45°

[tex]y = \sin(x) \cos(x) + \cos(x) \sin(x) \\ y = 2 \sin(x) \cos(x) \\ \frac{dy}{dx} = 2 \frac{d}{dx} ( \sin(x) \cos(x) ) \\ = 2( {cos}^{2} (x) - {sin}^{2} (x)) \\ = 2 \cos(2x) [/tex]
masukkan x = 45°
[tex]2 \cos(2 \times 45) = 2 \cos(90) = 0[/tex]