I’ve learned… How to properly label angles and side lengths, and what the sides of a triangle are called in relation to your chosen angle. You label the angles with upper case letters (A, B, C), and you label the side lengths with lower case letters (a, b, c). In relation to your chosen angle the side directly across from it is the “opposite” side, the longest side is the “hypotenuse”, and the other side is the “adjacent” side.

I’ve learned… What the formula for sin, cos, and tan (and what they do). All of these are used to find ratios and angles for right triangles, using their side lengths and an angle(s). The formulas for them are as follows:

Sin x = opp / hyp
Cos x = adj / hyp
Tan x = opp / adj

You would use these to find the ratio between side lengths (it takes the angle and gives you the ratio of the opposite side over the hypotenuse). There are also:

Sin^-1 x
Cos^-1 x
Tan^-1 x

These operations would give you the degree of an angle based on the different side lengths.

As an examples we can use sin x = opp/ hyp. This means that the sin for the degree x is the length of the opposite side of the triangle over (divided by) the length of the hypotenuse. Depending on what angle you are labelling or basing your triangle side names on, your equations will change for sin, cos, and tan.