单位圆在三角学中的地位是大家熟知的.本文试图从单位圆出发,给出三角函数值域、化asinx+bcosx成单名三角函数等问题的根据. 现行统编教材(中师、高中)中,在条件-1≤sinx≤1下得到了y=sinx的值域是〔-1,1〕.我们认为这样是不妥当的.在-1≤sinx≤1的条件下,只能说明y=sinx The position of the unit circle in trigonometry is well known. This article attempts to proceed from the unit circle and gives the basis for the trigonometric function range, asynx+bcosx into a single name trigonometric function, etc. The current textbook (secondary, high school) In the case of -1 ≤ sinx ≤ 1, the range of values ​​for y = sinx is [-1, 1]. We consider this to be inappropriate. In the case of -1 ≤ sinx ≤ 1, we can only specify y=sinx