+0  
 
+1
45
3
avatar

What rule is this? What is it called? Sin(2nX)/sin(nX) = 2Cos(nX)

 
Guest Aug 9, 2017
social bar
Sort: 

3+0 Answers

 #1
avatar+6672 
+1

What rule is this? What is it called? Sin(2nX)/sin(nX) = 2Cos(nX)

 

Hello guest!

 

sin 2x = 2 sin x cos x is one of the double angle functions

 

sin(2X)=2sin(X)*cos(X)


One can show this nicely over an addition theorem:


sin(x+y) = sin(x) * cos(y) + sin(y) * cos(x)
 

and this case has to do with double angles ...


sin(2x) = sin(x+x) = sin(x) * cos(x) + sin(x) * cos(x) = 2*sin(x)*cos(x)

 

laugh  !

 
asinus  Aug 9, 2017
 #2
avatar
+1

If I don't mind asking. Other than addition theorm what other rules do I need to learn, that is in the same level of learning, concerning sin and cos.

 

I'm abit behind in mathematics. I think half-angle trigonetric formulae is one of them.

 
Guest Aug 9, 2017
 #3
avatar+6672 
+1

Dear learner of trigonometry!

http://mathworld.wolfram.com/TrigonometricAdditionFormulas.html

Study this, please!
I wish you great success.

 

laugh  !

 
asinus  Aug 9, 2017

14 Online Users

avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details