Thursday

August 28, 2014

August 28, 2014

Posted by **Mitchel** on Sunday, February 17, 2013 at 11:33pm.

cos 4x + cos 2x = 2 - 2 sin^2(2x) - 2 sin^2 x

- Trig -
**Reiny**, Monday, February 18, 2013 at 12:32amusing the identity

cos 2A = cos^2 A - sin^2 A = 1 - 2sin^2 x = 2cos^2 x -1

LS = cos 4x + cos 2x

= cos^2 2x - sin^2 2x + cos 2x

= (1 - sin^2 (2x) ) - sin^2 (2x) + (1 - 2sin^2 x)

= 1 - 2sin^2 (2x) + 1 - 2sin^2 x

= 2 - 2sin^2 (2x) - 2sin^2 x

= RS

**Related Questions**

TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...

trig - it says to verify the following identity, working only on one side: cotx+...

Math - Calculus - The identity below is significant because it relates 3 ...

trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...

tigonometry - expres the following as sums and differences of sines or cosines ...

Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...

algebra - Can someone please help me do this problem? That would be great! ...

Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...

trig - For each expression in column I, choose the expression from column II to ...

trigonometry - Verify that following are identities: 1. cos 3t = 4 cosł t-3 cos ...