In Rt△ABC (right triangle), ∠C = 90, AB is the opposite side C of ∠ C, BC is the opposite side A of ∠A, AC is the opposite side B of ∠B, and the tangent function is tanB=b/a, that is, tanB=AC/BC. ?

Six basic functions:

Function name: sine function, cosine function, tangent function, cotangent function, secant function, cotangent function.

Sine function: sinθ=y/r

Cosine function: cosθ=x/r

Tangent function: tanθ=y/x

Cotangent function: cotθ=x/y

Secθ=r/x secθ = r/x

Cotangent function: csθ= r/y