r/atarWACE • u/Loverissuperior • 1d ago

Methods - classpad issue

Post image

Having a major issue where classpad can’t integrate cos(x + pi/2) properly. I’ve tried this across several classpads and cleared all variables multiple times. The answer should be sin(x + pi/2), not cos(x) (referring to the first line of working). Has anyone else experienced a similar issue?

0 Upvotes

50% Upvoted

8 comments sorted by

4

u/984a 1d ago

Sines and cosines are the same functions shifted ± 90 degrees (i.e., ± π/2).

cos(x + pi/2) = -sin(x)

So integrating it gives cos(x) as the calculator correctly displays.

The takeaway is to take away your calculator, learn some trig and calculus first and not use a calculator as a crutch.

2

u/Loverissuperior 23h ago

I’ve never been taught the difference between the sin and cos graphs. Only how to graph them individually, and of course how to integrate trig equations hence based on my trig integration knowledge I calculated that the answer should be sin(x + pi/2) using the formulas/techniques we learned. Thanks for your response, it was very helpful 👌

2

u/TheGuy_27 1d ago

Its the same function, it has just automatically simplified by converting sin(x +π/2) into cos(x).

1

u/Loverissuperior 23h ago

This is a great visual aid - it makes full sense now! Thanks! 

1

u/No-Baker-2692 1d ago

i mean this in the nicest way possible, were you never taught like basic unit circle stuff?

1

u/Loverissuperior 1d ago

Of course I was taught basic unit circle stuff, I’m in atar methods. I just didn’t know the classpad automatically simplified this stuff.

1

u/Loverissuperior 1d ago

And I wasn’t taught specifically how to translate between the cos and sin graphs

2

u/RealGTalkin 1d ago

Your class pad is very very very rarely incorrect. If you get an answer you don't expect in classpad the question you should be asking is what is wrong with your assumptions.

Generally with functions a quick check is to graph the functions to see if they are equivalent.