"Common trigonometric functions include sine, cosine, and tangent functions. In other disciplines such as nautical science, surveying, engineering, and so on, we also use other trigonometric functions such as cotangent, secant, cosecant, versed sine, versed cosine, half versed sine, half versed cosine, etc."
"Additionally, using trigonometric functions as templates, we can define a similar class of functions called hyperbolic functions. Common hyperbolic functions are also referred to as hyperbolic sine, hyperbolic cosine, and so on."
Bi Xia pointed at the right triangle, "In a right triangle, when the three points A, B, and C on the plane are connected, AB, AC, and BC form a right triangle, with ∠ACB being the right angle. For ∠BAC, the opposite side a=BC, hypotenuse c=AB, and the adjacent side b=AC."
