If $sinx=(4/5)$ , how do you find $sin2x$ ?

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Answer 1 · 2016-04-11T05:53:11

$sin2x = 2*4/5*3/5=24/25$

Since $sinx=4/5$ we have a (3, 4, 5) triangle and we can totally define all sines and cosines, $cosx=3/5$

Now we use the double angle identities:
$sin2x=2sinx*cosx$
$sin2x = 2*4/5*3/5=24/25$

If sinx=(4/5)sinx=(4/5), how do you find sin2xsin2x?