Trigonometry problems,help plz

1. state the three double angle formulas for the cosine function
2. state the three pythagorean identities in trigonometry?
3.write the slope formular
4.simplify e^(ln8x)

1) cos(2x)
=(cosx)^2-(sinx)^2
=2(cosx)^2-1
=1-2(sinx)^2
#2)(sinx)^2+(cosx)^2=1
(tanx)^2+1=(secx)^2
(cotx)^2+1=(cscx)^2
#3) slope (a,b) (c,d) = (b-d)/(a-c)
#4) e^ln(8x) = 8x