# Square trig graphs

## Main Question or Discussion Point

We had a test recently in trig on graphing trig functions. I found it all quite simple except a problem that we had not discussed. I believe the problem was something like y=cos^2(x). I graphed it by squaring each cosine value, because i had no idea what else to do, but when i turned the test in, my teacher told me that it was only half correct. I ended up with a nice M (maybe W) shape. Thinking back, would it have been correct to change the equation to y=(1+cos2x)/2 and then graph it?

symbolipoint
Homework Helper
Gold Member
tycon69, what are you trying to express? Are you asking about [cos(x)]*[cos(x)], or what? You seem to mean just that. All the values will be positive (the 'y' values). The 'M' shape that your teacher indicated. The amplitude is 1.

Maybe you took the squares of negative cosines as negative? cos^2(x) is greater than 0 everywhere, was your graph?

yes it was, it's amplitude was one and everything was above 0. I just graphed it on a graphing application and the graph is identical to what i graphed. I must have overlooked a simple mistake, i'll have to look at it monday. Luckily she only counted off half so i ended up with an A. Thx for trying to help me, i know my explanation was quite confusing.

HallsofIvy
Yes, the problem was just to graph the function. I found out it was a pretty stupid mistake on my part in that i graphed cos(0)=0 when it should have of course been 1 