Trig proving (1 Viewer)

[Bostick]

Show sin 8x = 4sin2xcos^3*2x-4sin^3*2xcos2x

PS: How do you you use Latex when making a thread, where do I click for the option?

 

[thongetsu]

sin(4x + 4x) = sin4xcos4x + sin4xcos4x
= 2sin4xcos4x
sin4x = sin(2x + 2x)
=2(sin2xcos2x + sin2xcos2x)(cos4x)
=2(2sin2xcos2x)(cos4x)
=4(sin2xcos2x)(cos4x)
cos4x = cos(2x + 2x)
=4(sin2xcos2x)(cos2xcos2x - sin2xsin2x)
=4(sin2xcos2x)(cos^2*2x - sin^2*2x)
=4(sin2x.cos^3*2x - sin^3*2x.cos2x)
= 4sin2xcos^3*2x-4sin^3*2xcos2x

LHS = RHS

 

[Ferox]

I thought angle-sum was 3 unit.

 

[thongetsu]

oh..i didnt notice where the thread was. I'm pretty sure this is a 3unit Q.

 

[Bostick]

whoops put it in the wrong section lol, anyway thanks for the help

 

[bouncing]

latex equation editor is right above the quick reply box