Differentiate y=sin²t-cos²t

[DearSky]

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When differentiating y=sin²t-cos²t, wouldn't it be 4sintcost? My friend got a different answer.. it's driving us up the wall.

 

[rxfordummies]

I got the same as yours:
= (sint)² + (cost)²
= 2sintcost - 2cost(-sint)
= 4sintcost

 

[ephemeralsun]

your answer is correct

 

[MilkmanAl]

SDN isn't a place for homework answers. Closeified.