Are you squaring the trig. functions when you test with your calculator?
How does that work? I've tried it with various values on the calculator and it's not equal. eg cos4 - 1 is not equal to -sin4 (if theta = 2). If neccesary, I can post the entire question. It concerns limits.
I've got an old fx-82. I don't have any option to square the actual trig function, but I should be able to square the x value right?
let theta = x (because it's quicker to write)
so let x = 2
cos^2(x) -1 = cos4 -1 = -0.002
-sin^2(x) = -sin4 = -0.07
No idea what I am doing wrong..
edit: Actually, it should be (cosx)^2 right? not what I am doing. I think I got it.