In a right triangle, when the connecting lines AB, AC and BC of three points A, B and C on the plane form a right triangle, where ∠ACB is a right angle. For ∠BAC, for the opposite) a=BC, hypotenuse) c=AB, and adjacent) b=AC, there is the following relationship:

Sin is the hypotenuse of contrast, for example, sin ∠ BAC = a/c.

Cos is the hypotenuse of the adjacent side, for example, cos ∠ BAC = b/c.

Tan is the opposite side of the adjacent side, for example, tan ∠ BAC = a/b.

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