I need help in math-trigonometry?

i have a test tomorrow on the basics of trigonometry. it should be easy but for some reason i have drawn a blank in my brain to this and i cannot figure out the cosine, sine, and tangent to simple right angle triangles. its embarring. I need a nudge from someone who is intellect with this subject. i won't bother for too long. once i get over this hump i should be o:k .