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avatar+1075 

Umm, why is trig so hard. Take this problem as an example. 

 

1. Find the maximum value of  \(5cosA + 12sinA + 12\)

 

And good luck with this one...it's literally impossible. I don't even know where to start. 

 

2. If tan θ + sec θ = l, prove that sec θ = (l^2 + 1)/2l

 

Thanks!

 Jun 18, 2024
 #1
avatar+129690 
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1.  5cos A + 12sinA + 12        take the derivative and set to 0

 

-5sinA  + 12 cos A  =  0

 

12cos A = 5sinA

 

sinA / cos A  = 12/5

 

tan A  = 12/5

 

cos A =  5/13       sin A =  12/13

 

The max value is

 

5 (5/13)  + 12 (12/13) + 12   =   (25 + 144) / 13 + 12  =  169/13 + 12  =  13 + 12 =  25

 

 

cool cool cool

 Jun 18, 2024

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