[Gary Oak]

Pythagorean Theorem.
He states, that a^2+b^2 equals to c^2
This is used to find the missing length of one of the sides on a triangle.
(If your triangle is 90 Deg then you can easily find the Volume and so on.)

- Then you can go on:
The sine of an angle is the ratio of the length of the opposite side to the length of the hypotenuse. (The word comes from the Latin sinus for gulf or bay,[1] since, given a unit circle, it is the side of the triangle on which the angle opens.) In our case
\sin A = \frac {\textrm{opposite}} {\textrm{hypotenuse}} = \frac {a} {h}.
Note that this ratio does not depend on the size of the particular right triangle chosen, as long as it contains the angle A, since all such triangles are similar.
The cosine of an angle is the ratio of the length of the adjacent side to the length of the hypotenuse: so called because it is the sine of the complementary or co-angle.[2] In our case
\cos A = \frac {\textrm{adjacent}} {\textrm{hypotenuse}} = \frac {b} {h}.
The tangent of an angle is the ratio of the length of the opposite side to the length of the adjacent side: so called because it can be represented as a line segment tangent to the circle, that is the line that touches the circle, from Latin linea tangens or touching line (cf. tangere, to touch).[3] In our case
\tan A = \frac {\textrm{opposite}} {\textrm{adjacent}} = \frac {a} {b}.
The acronyms "SOHCAHTOA" ("Soak-a-toe", "Sock-a-toa", "So-kah-toa") and "OHSAHCOAT" are commonly used mnemonics for these ratios.


(A triangle has A B C and a b c. I'm in tenth grade, exams are close up, and shit I don't even get sine tangens or cosine, you know what? I don't give a fuck. xD)