g(θ) = 20θ − 5 tan θ
To find out critical points we take first derivative and set it =0
g(θ) = 20θ − 5 tan θ
g'(θ) = 20 − 5 sec^2(θ)
Now we set derivative =0
20 − 5 sec^2(θ)=0
Subtract 20 from both sides
− 5 sec^2(θ)=0 -20
Divide both sides by 5
sec^2(θ)= 4
Take square root on both sides
sec(θ)= -2 and sec(θ)= +2
sec can be written as 1/cos
so sec(θ)= -2 can be written as cos(θ)= -1/2
Using unit circle the value of θ is 
sec(θ)= 2 can be written as cos(θ)=1/2
Using unit circle the value of θ is 
For general solution we add 2npi
So critical points are

Answer:
-18x+8
Step-by-step explanation:
First you have to distribute the -2 to the 3x and the -5 in the parenthesis giving you -6x+10-12x-2.
Next you combine like terms which gives you -18x+8

÷

Multiply

by the reciprocal of

, which is

=

×

=

We can simplify it further:
The greatest common factor here is
168
=
The height of the envelope is 10. This is because you divide the area by 3. So, the missing side is 10 inches.