Last post please please help!! Algebra 2, 4 questions

Question 1

.4 (.91)^2

The .4 means that .4 (100) = 40 pounds were originally in stock

The    .91 means that  the stock decreased by 9%  every hour

Question 2

This is an increasing exponential function

% change = [240 - 100]  = 140%

Question 3

Theta is in the third quadrant.....the sine and cosine are negative....so...tan > 0

cos (- theta)  =   -cos(theta)

And cos theta   =  [- sqrt [ 5^2 - 3^2] / 5   =  - sqrt (16)/ 5  =  -4/5

So

cos (-theta) = -cos(theta )   =  - (-4/5)   = 4/5

Question 4

tan  ( pi +  x)   =

sin (pi + x)             sin pi cos x  + cos pi sin x                        -sinx

_________   =       _________________________  =         ______ =    tan x   =   2/5

cos ( pi + x)            cos pi cos x  -  sin pi  sin x                     -cos x