Posted by **tom** on Monday, December 24, 2012 at 8:00am.

Express sin 2x cos 4x as a sum of trigonometric functions

- maths -
**MathMate**, Monday, December 24, 2012 at 10:03am
From the familiar

sin(A+B)=sin(A)cos(B)+cos(A)sin(B), and

sin(A-B)=sin(A)cos(B)-cos(A)sin(B)

Add both equations to get

sin(A+B)+sin(A-B)=2sin(A)cos(B) .....(3)

But

2x=3x-x

4x=3x+x,

so substitute A=3x, B=x into equation (3) and simplify to get your answer.

## Answer This Question

## Related Questions

- maths - Express sin 2x cos 4x as a sum of trigonometric functions.
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- Math(Correction) - Use the given function values and trigonometric identities (...
- Trig - sum and difference formulas - Write the expression as a single ...
- calculus/Trig - Suppose you wish to express sin(3t) in terms of sint and cost. ...
- CALCULUS - If cos(t)=–7/9, find the values of the following trigonometric ...
- trig - Establish the trigonometric identity (Hint: Use sum to product) cos(5x)+...
- TRIGONOMETRY - Write the following trigonometric expression as an algebraic ...
- Math(Correction) - Use the given function values and trigonometric identities (...

More Related Questions