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Exams coming up.. and here are a few practice examples throughout the course (elem algebra, calculus) that i have been stuck on that would appreciate some help with.

**1)**find all solutions for cot^2(x) = 1, in the interval 2*pi <= x < 4*pi

seeing cot = 1/tan, then solving for x would equal = 0.017455.. giving me no obvious angle to find in the intervals stated (like i would do for similar examples).

**2)**

P(x) = [tex]\frac{1-sin(x)}{cos(x)}[/tex]

p'(x) = [tex]\frac{-cos(x)*cos(x) - (1-sin(x))(-sin(x)}{cos^2(x)}[/tex]

= [tex]\frac{-cos^2(x)*cos(x) + sin(x)-sin^2(x)}{cos^2(x)}[/tex]

= [tex]\frac{sin(x)-1}{cos^2(x)}[/tex]

i don't understand where the -cos^2(x)*cos(x) comes from in the third line, shouldn't this just be -cos^2(x)? and i don't understand the fourth line either.

will post the rest of the questions once i have these 2 worked out .