Trig question: I am being asked to graph one period ending with x=2 pi. I I have graphed it (with no graphing calculator) and do not understand the solution at the end of my book. I think the y min. and y max. should by 1 and -1. Why does the book say it is 1.2 and -1.2?

Question

Trig question:  I am being asked to graph one period ending with x=2 pi.  I I have graphed it (with no graphing calculator) and do not understand the solution at the end of my book.  I think the y min. and y max. should by 1 and -1.  Why does the book say it is 1.2 and -1.2?

anonymous · Answer

Hmmm. Off the top of my head, I would say you are right. What was the equation you were asked to graph one period of?

anonymous · Answer

y=cosx - Graph one period ending at x=2Pi. 
The book asks to record xmin,max,scl & y min, max, scl. 
First time I have taken Trig.  Just trying to figure out why this is 1.2 and not 1?

anonymous · Answer

Well, the book could be wrong, couldn't it? The maximum value of the cosine curve is 1. No question about it. And the minimum value of cosine is -1.

Ahh ... I think the book is giving you the y min and y max of the calculator's WINDOW, not the y min and y max of the curve itself. That would give a little margin around the curve. Does that make work for you? (That IS what the TI calculator window calls the vertical scale.)

anonymous · Answer

Thank you so much!! That makes total sense now.  I have been pulling may hair out for like an hour till I found this website.  Yes the book does ask to use  a graphing calculator.

anonymous · Answer

Great. Too bad about the hair.