But the question is currently allowing the students to just enter the function as it was and giving them credit for it.
Is there a way to use bizarro math to require only a single sine function?
Or maybe just a way to check that the function includes a "sin" but not a "cos"? Maybe with a custom grader?
Can I check the string of their answer contains "sin" and not "cos" this way and still check the functional answer using a MathObject Function? If so, this may be the easiest way to make this problem behave as it should without making it require a number of answer blanks.