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Idealist
 3 years ago
Find the second derivative of f(x)=sinxcosx.
Idealist
 3 years ago
Find the second derivative of f(x)=sinxcosx.

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inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0Well, what's the first derivative?

inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0use the product rule...

Idealist
 3 years ago
Best ResponseYou've already chosen the best response.0The first derivative is (cosx)^2(sinx)^2. But how do I take the derivative of that?

inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0well, remember that cos(a+b)=cos a cos bsin a sin b...

inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0in other words, use the double angle formula for to reduce the following expression you have obtained. And then use the chain rule.

Sujay
 3 years ago
Best ResponseYou've already chosen the best response.2\[f'(x)=cosx(\cos(x))+(\sin(x)\sin(x))\] Product Rule and Derivatives of Trigs Simplify. \[f'(x)=\cos ^{2}x\sin ^{2}x\] \[f''(x)=2\cos(x)(\sin(x))2\sin(x)(\cos(x))\] Derivative of Trig and Chain Rule

hcmathkim
 3 years ago
Best ResponseYou've already chosen the best response.0bring the power down, keep the inside, differentiate inside

inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0Since no one seems to get it USE COS^2 XSIN^2 X=COS(2x) TO SIMPLIFY EXPRESSION

inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0simplified expression is dy/dx=cos(2x) then take the dervative of that

inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0@Idealist are you followign?

Idealist
 3 years ago
Best ResponseYou've already chosen the best response.0Yes. I got it. Thanks for the help, guys.

inkyvoyd
 3 years ago
Best ResponseYou've already chosen the best response.0I like medals. LOL but yeah, nice to see :) let me know your final answer so I can check it
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