Sample calculation from a university exam I am grading

[luzula]

cos(x + 90°) = 0
cos = −(x + 90°)

Aaaaaaaahhhh...

Comments

[isis]

Oh, HEE, there are so many things wrong with that I have to laugh! (Obviously it should be cos = 0/(x+90)! *ducks*)

Seriously, that is an impressive work of doin' it rong.

[luzula]

Yes, it is a true pearl, far beyond the mundane errors of most exams...

[sproid]

A. Very Wrong and B. How did they progress from there? Now they have *two* unknowns! "cos" and "x"!

[luzula]

Who knows? *throws up hands* The exam is buried deep in my pile now and I can't remember how it continued...