ok am making a flash game and need some help in writing a formula for it

basically user will select power and angle
character will then jump depending upon the values user entered

i need however to figure out depending upon power, angle and a fixed value for gravity where the peak of a curve will be so that character then starts to fall again

so that the characters x/y postion increases until they reach peak of curce and then start to decrease again

what equation could i use to calculate this?

v_Ln