My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
November 20th, 2012, 05:31 PM   #1
Newbie
 
Joined: Feb 2012

Posts: 6
Thanks: 0

double angle problem

Hi, here's the question

simplify the given expression;
sin3x - cos3x
sinx cos x

just not sure which special product to use here?
sin2a=2sinacosa is my guess but I don't know how to accommodate the 3x with that.
Anybody able to help?

If I take LCD, I end up with sin2x-cos2x/ sinxcosx.
Mike7remblay is offline  
 
November 20th, 2012, 05:41 PM   #2
Global Moderator
 
Joined: Dec 2006

Posts: 21,018
Thanks: 2251

sin(3x)cos(x) - cos(3x)sin(x)
--------------------------------- = sin(3x - x)/((sin2x)/2) = 2
            sin(x)cos(x)
skipjack is offline  
November 20th, 2012, 05:56 PM   #3
Newbie
 
Joined: Feb 2012

Posts: 6
Thanks: 0

Re: double angle problem

Thanx for the reply.
still curious how the cos products turned into cos products?
was the sin2a=2sinacosa formula used?
Mike7remblay is offline  
November 21st, 2012, 09:27 AM   #4
Global Moderator
 
Joined: Dec 2006

Posts: 21,018
Thanks: 2251

There were no cos products that turned into cos products!
skipjack is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
angle, double, problem



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Double angle formula TomCadwallader Algebra 2 October 7th, 2013 11:22 AM
Double-angle Formulae bilano99 Algebra 2 November 6th, 2012 10:09 AM
how to double an angle with paperfolding studentx Abstract Algebra 4 May 25th, 2011 05:52 AM
Double angle formulae hoyy1kolko Algebra 1 May 5th, 2011 06:54 AM
Multiple Choice Problem on Using Double-Angle Formulas peteglenn Algebra 1 September 16th, 2009 03:41 PM





Copyright © 2019 My Math Forum. All rights reserved.