Projectile Vector Equation - Headache!!?

Question

Given:
distance d the projectile launcher from a wall
angle A the projectile is launched at
vi the velocity [vector] it is launched at

With the information, I conclude that:
x(t) = (vi*cosA)t
y(t) = (vi*sinA)t - 1/2 g t^2 g being the gravitational constant.

Now, I have to write y in terms of x [suggestion was 'eliminating' the t]. I have extremey difficulty doing so, please assist!

Answer 1

t=x/(vi*cosA)
y(t)=(vi*sinA)*x/(vi*cosA) -1/2 g*[x/(vi*cosA)]^2
==>
y(t)=
x*tan(A)-[(g*x^2)/(2vi^2)]
*(1/(cosA)^2)
and
1/(cosA)^2=1+(tanA)^2
==>
y(t)=
x*tan(A)-[(g*x^2)/(2vi^2)]
*(1+(tanA)^2)

Answer 2

it's pressure that you place upon yourself. if you are reading something hard to understand, read only one sentence at a time. get that sentence understood and then change it into your own words. now read the next sentence and do the same. never continue with a new sentence if you didn't understand the last unless the next sentence is intended to further explain the previous one. i got by most of these problems in college and was a straight a student because i have been blessed with photographic memory. when asked a question i simply flip through the pages of the textbook in my mind and look up the answer. i wish you well in your studies. and if i could give you my gift i would because i no longer have need of it.