How do you do these wave function graphs

i do not know how to find the y-values. there are so many variables that i can't figure out, a, A

1)
http://oi45.tinypic.com/2ujjdli.jpg

2)
http://oi46.tinypic.com/15s7ehf.jpg


some additional info ; http://oi45.tinypic.com/2vto6zk.jpg


thanks in advance, i am stuck

a wave function is a rule connecting the Y amplitude to both time and place
they have formulas with a sin and cos of some variable time or distance
because sin and cos trig functions swing between plus and minus one the value of y rises and falls

start with a simple time graph

y displacement = A maximum swing ( units of distance) * sin of (theta angle)
the angle is in radians a pure number having no units

the angle theta is t varying time/ T time for one full swing
when theta = 0 = 2Pi, = 2 * 2PI ... the sin is zero,
sin Pi/2 ( 90 deg) = 1; sin 3/2 PI = - 1

make a chart of fractions of a full circle and plot it it will rise and fall like the ripple on a pond

As I see it, the letter is a is a constant and x/a is a simple ratio of displacement to whatever a represents. So, there is really only one variable, x.