Given,

y =

Using (a + b)² = a² + 2ab + b²

y =

⇒ y = {∵ sin²A + cos²A = 1 & 2sin A cos A = sin 2A}

⇒ y = 1 + sin x

Now, differentiating both sides w.r.t x –

∴ sin x)

Using algebra of derivatives –

⇒

Use:

∴

Hence, dy/dx at x = π/6 is