Calculator Help PLEASE !! (trig)

Hi, I'm using a graphics calculator and practicing trigonometry, I'm trying to do cosine law where you find out the angle:

CosA = b² + c² - a²
---------------
2bc

I'm working out: CosA= 6.3² + 5.4² - 6.04²
------------------------
2(6.3)(5.4)

I know it's supposed to equal around 0.4757 which I then use cos-1 to get 61.6 degrees as the angle, BUT my calculator (and another one I used) keeps giving me negative numbers whenever I do this formula, for this specific equation I get like negative -551.702016.... WHY DOES MY CALCULATOR KEEP DOING THIS ?!?! Ive used it before and it worked, I tried resetting and it still won't give me the correct answer :( its in degrees mode too...

Please help me, how can I get it to give me the correct answer ? And not negatives :(

Well, I'm no expert in maths, to be completely honest. But I've recently done this maths. I typed in the equation into the calculator and also got the negative number. But when I inputted 6.3² + 5.4² - 6.04², pressed the equal sign and then put in the rest of the equation (2(6.3)(5.4)), I received a positive answer.

Sorry, graphic calculators are NOT allowed in tests!

You must be substituting it incorrectly in your calculator or you don't know how to use a scientific calculator properly or they are just not good as scientific calculators.