How can I write 1/3 sec u in terms of x?
So if I am understanding correctly, you want to write
in terms of x where you use the equation
Well, we know that , thus
We also know the mother of all identities is which can be solved for as
Now, using the equation do you think you can finish this?
Also, when Soroban found that , he found it by taking the square root of , so it should have been , if you prefer to look at it this way.