Solution of \frac{d}{d\theta} \left( \cos(2\theta) \right)

Solve fracddtheta ( cos(2theta) )

Evaluate

\frac{d}{d θ} (cos (2 θ))

Use the chain rule \frac{d}{d x} (f (g)) = \frac{d}{d g} (f (g)) \times \frac{d}{d x} (g) where the g = 2 θ, to find the derivative

\frac{d}{d g} (cos (g)) \times \frac{d}{d θ} (2 θ)

Use \frac{d}{d x} (cos x) = - sin x to find derivative

- sin (g) \times \frac{d}{d θ} (2 θ)

Calculate

More Steps

- sin (g) \times 2

Substitute back

- sin (2 θ) \times 2

Solution

- 2 sin (2 θ)