WeBWorK has the usually useful feature that it will not distinguish between any equivalent expressions. For example if I asked you to express $\sin^2 x$ in terms of $\cos x$, and told ww that the correct answer is $1- \cos^2 x$, then WeBWorK would be just as happy if you typed $sin^2 x$, and so bypassed the entire problem!
To finesse this feature we have to do something contrived. In each of the next few problems I will tell you to use a different variable for certain things.
Here is an easy warm up question and illustration:
Use $C$ to denote $\cos x$, and express $\sin^2 x$ in terms of $C$: $\sin^2(x) =$ .
Since $\sin^2x+\cos^2 x = 1$, in this case you would of course enter $$1-C^2$$ as your answer. You can type it, for example, as 1-C**2 . If you feel adventurous you can also type (1-C)(1+C), but you must use $C$ instead of $\cos x$!
Note that mathematics and WeBWorK are case sensitive , so you must use upper case C in this problem. For the fun of it you might check the cryptic error message you get when you use a lower case c or some other variable!
Computers are fun! Let's see if you got all this. Use $S$ to denote $\sin x$, and express $\cos^2 x$ in terms of $S$: $\cos^2(x) =$ .