## zaqwsx Group Title prove that sin20 sin40 sin60 sin80=3/16 one year ago one year ago

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1. shubhamsrg

What is your attempt so far?

2. TO!RAW!FOR!LIFE

calculator.lol dats all you need

3. Yahoo!

Hint: $sinx.\sin(60-x).(\sin60+x) = \frac{ \sin 3x }{ 4 }$

4. sriramkumar

sin60 is $\sqrt{3}/2$ right? put it there in that, and then apply the above formula you'll get it... $\sqrt{3}/2$ * sin60/4 = 3/2*4*2 = 3/16