Register to reply 
What does (cos(2x))^2 equal?by justine411
Tags: cos2x2 
Share this thread: 
#1
Apr1107, 10:11 AM

P: 16

1. The problem statement, all variables and given/known data
(cos2x)^2 2. Relevant equations 3. The attempt at a solution I'm not sure if it is cos^2(2x) or cos^2(4x) or what. Should I use an identity to simplify it to make it easier to solve? Please help! :) 


#2
Apr1107, 12:13 PM

P: 2,046

What is there to solve???
(cos2x)^2 is just an expression. 


#3
Apr1107, 02:02 PM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,503

In what sense is (cos(2x))^{2} a "problem"? What do you want to do with it?
I will say that (cos(2x))^{2} means: First calculate 2x, then find cosine of that and finally square that result. Notice that it is still 2x, not 4x. The fact that ^{2} is outside the parentheses means that it only applies to the final result. 


#4
Apr1207, 06:46 AM

P: 14

What does (cos(2x))^2 equal?



#5
Apr1207, 06:54 AM

Admin
P: 21,866

cos^{2}y = cos y * cos y. There are also particular trigonometric identites with which one should be familiar, i.e. cos (x+y) and sin (x+y). 


#6
Apr1207, 07:49 AM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,503

You still haven't told us what the problem was! Was it to write (cos(2x))^2 in terms of sin(x) and cos(x)? I would simply be inclined to write (cos(2x))^2 as cos^2(2x).



Register to reply 
Related Discussions  
Solve 2+cos2x=3cosx  Calculus & Beyond Homework  1 