Find a,b Parameters for Function to Get Extreme Value

[Fatlum]

Find a, b parameters such that the function such that the function $f(x)= (sin²x)/(a-bcosx)$ has extreme value in point (pi/3,1/4)

 

[tiny-tim]

Welcome to PF!

Hi Fatlum! Welcome to PF!

Show us what you've tried, and where you're stuck, and then we'll know how to help!

 

[Fatlum]

I understand that in this point the derivative should be 0. So I found the derivative ,equaled to zero and I replaced (pi/3=x) . But I'm not sure, should I equal the function with 1/4 to find the ordiante ?

 

[tiny-tim]

using only sinx = π/3 will only give you the ratio a/b

you need to use y = 1/4 to find what they actually are

 

[Fatlum]

Thank you very much tiny-tim. I found now the paramters. a=5 and b=4.