Question #79582

Question

7006 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-10-30T22:06:23

This is just a trig question to get the solution into a different form;

Recall the sine addition formula:

$sin (A+ B) =sinAcosB + cosAsinB$

Put $A=B$ to get a double angle formula;

$sin (A+ A) =sinAcosA + cosAsinA$
$:. sin (2A) =2sinAcosA$

If we put $A=2x$ then;
$:. sin (2(2x)) =2sin2xcos2x$
$:. sin 4x =2sin2xcos2x$

Hence, $sin2xcos2x = 1/2sin 4x$