# Problem of the Week

## Updated at Jan 6, 2014 12:14 PM

To get more practice in calculus, we brought you this problem of the week:

How can we solve for the derivative of $$\ln{(\sec{x})}$$?

Check out the solution below!

$\frac{d}{dx} \ln{(\sec{x})}$

 1 Use Chain Rule on $$\frac{d}{dx} \ln{(\sec{x})}$$. Let $$u=\sec{x}$$. The derivative of $$\ln{u}$$ is $$\frac{1}{u}$$.$\frac{1}{\sec{x}}(\frac{d}{dx} \sec{x})$2 Use Trigonometric Differentiation: the derivative of $$\sec{x}$$ is $$\sec{x}\tan{x}$$.$\tan{x}$Donetan(x)