Need help for maths ext question. (1 Viewer)

der311 · Aug 3, 2011

how do you simplify 2cos3xsin3x???

SpiralFlex · Aug 3, 2011

$2 \sin 3x \cos 3x$

We can recall the identity of,

$\sin 2a = 2\sin a \cos a$

So we can do the same thing with our expression. Hence,

$=\sin 6x$

Note: If you cannot see it straight away then it's a good idea to let $a=3x$ .

$=2\sin a \cos a$

$=\sin 2a$

$=\sin 2(3x)$

$=\sin 6x$

Can I have a reward? Prehaps a bite?

AAEldar · Aug 3, 2011

der311 said:
how do you simplify 2cos3xsin3x???

$2cos(3x)sin(3x) \\ =sin(6x)$

Straight from the identity $sin(2x)=2sinxcosx$ .

EDIT: Ninja'd D:

Need help for maths ext question. (1 Viewer)

der311

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SpiralFlex

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AAEldar

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