What is π-6 of cos and π-6 of sin?

Cos (π/6) =cos 30 degrees = (root number 3)/2.

Sin (π/6) =sin 30 degrees = 1/2.

π,π/2,π/3,π/4 ... and so on, become an angle and ask again.

In a right triangle, the ratio of the opposite side to the hypotenuse of ∠ α (not a right angle) is called the sine of ∠α, which means that sinα=∠α = the opposite side of ∠α/the hypotenuse of ∠α.

. Sinα counts as sinus in Latin.

In the old saying, sine is the ratio of hook to string.

The "string" in the ancient "hook three strands, four strings and five" is the hypotenuse in the right triangle.

The thigh is a human thigh. The ancients called the long right side of a right triangle "thigh".

References:

Sin-sogou encyclopedia