Integrate sec^22x
![Integrate sec^22x](integrate-sec_2_2x/step-01.gif)
To integrate sec^22x, also written as ∫sec22x dx, sec squared 2x, (sec2x)^2, and sec^2(2x), we start with a u substitution.
![u substitution](integrate-sec_2_2x/step-02.gif)
Let u = 2x. This is a simple u substitution.
![du/dx](integrate-sec_2_2x/step-03.gif)
Therefore du/dx = 2. This is a simple differentiation step.
![Expression for dx](integrate-sec_2_2x/step-04.gif)
We rearrange the previous expression for dx.
![Equivalent integral in terms of u.](integrate-sec_2_2x/step-05.gif)
We now have another integration on the RHS that means the same thing but is in terms of u.
![formula [1]](integrate-sec_2_2x/step-06.gif)
We move the constant 1/2 outside of the integral to simplify.
![Standard integration solution.](integrate-sec_2_2x/step-07.gif)
We recall a standard integration solution usually found in formula booklets. We also proved it in the article integrate sec^2x.
![Integral of Sec^2u du = tanu](integrate-sec_2_2x/step-08.gif)
Therefore in our case, we can integrate in terms of u, to give the answer, as shown above.
![Part answer.](integrate-sec_2_2x/step-09.gif)
We substitute the answer back into equation [1] and reintroduce the constant 1/2.
![Recall u=2x](integrate-sec_2_2x/step-10.gif)
We recall that u=2x, and we can substitute that back in as well.
![Final answer.](integrate-sec_2_2x/step-11.gif)
Hence this is the final answer.