sin = opposite/hypotenuse
cos = adjacent/hypotenuse
tan = opposite/adjacent
So, for example, the angle theta being between 1 and 3, the opposite is line 2, and the adjacent line 1, and the hypotenuse line 3.
cos = adjacent/hypotenuse
tan = opposite/adjacent
So, for example, the angle theta being between 1 and 3, the opposite is line 2, and the adjacent line 1, and the hypotenuse line 3.