The graph of the cosine is the darker curve; note how it's shifted to the left of the sine curve. The graphs of y = sin x and y = cos x on the same axes. . .. You probably noticed that these cofunction identities all use the difference of angles, but the slide of the sine function to the left was a sum.
The sine of the angle = the length of the opposite side. the length of the hypotenuse.
The cosine of the angle = the length of the adjacent side. the length of the hypotenuse.
The tangent of the angle = the length of the opposite side. the length of the adjacent side.
