How? Which Trig Identityis that?

  • Thread starter k31453
  • Start date
  • #1
58
0
How?? Which Trig Identityis that?

Homework Statement


[Broken]



Homework Equations





The Attempt at a Solution


sin^2 = 1- cos^2 ??
 
Last edited by a moderator:

Answers and Replies

  • #2
lurflurf
Homework Helper
2,440
138
That looks wrong. It is close to the identity.

$$2\sin^2(x-\pi/4)=1-\sin(2x)$$
 
  • #3
ehild
Homework Helper
15,543
1,914
Yes. one of the relevant equation is sin2θ=1-cos2θ.
The other one is cos(2θ)=cos2θ-sin2θ. From these, you get the identity

sin2θ=.5(1-cos(2θ)). Use it.


ehild
 
  • #4
58
0
Yes. one of the relevant equation is sin2θ=1-cos2θ.
The other one is cos(2θ)=cos2θ-sin2θ. From these, you get the identity

sin2θ=.5(1-cos(2θ)). Use it.


ehild

but there is no sin..
 
  • #5
ehild
Homework Helper
15,543
1,914
but there is no sin..

The equation you wrote in the first post is wrong. Correctly, it should be:

2000sin2(500πt)=1000(1-cos(1000πt)).

ehild
 
  • #6
58
0
The equation you wrote in the first post is wrong. Correctly, it should be:

2000sin2(500πt)=1000(1-cos(1000πt)).

ehild

Awaks.. IT is solution of the Electrical Engineer : priniciples and application Hambley book.

And they made it wrong. I asked the question though i was wrong.
 

Related Threads on How? Which Trig Identityis that?

  • Last Post
Replies
5
Views
3K
  • Last Post
Replies
11
Views
1K
  • Last Post
Replies
1
Views
854
Replies
3
Views
1K
  • Last Post
Replies
2
Views
4K
F
Replies
3
Views
830
Replies
4
Views
2K
Replies
3
Views
2K
Replies
11
Views
798
Replies
3
Views
4K
Top