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高中代数(必修)上册第4.2节最后指出“…,显然sin(arcsinx)=x,其中x∈[-1,1],但是arcsin(sinx)不一定等于x,而是等于在闭区间[-π/2,π/2]上与x有相同正弦的一个值”,教材在这里明确指出了sinx的反正弦与x的关系,教学中经常发现一些学生由于对这段文字不重视或理解的不准确,而造成解题失误,为了进一步明确这种关系,我们不妨将这段文字写成公式:
High school algebra (required) in the first section of the first section of the book states that “..., obviously sin(arcsinx) = x, where x ∈ [-1, 1], but arcsin (sinx) is not necessarily equal to x, but is equal to the closed interval [- π/2, π/2] and x have a value of the same sine,” teaching materials here explicitly pointed out the relationship between sinx arcsine and x, often found in teaching students because of this text does not attach importance or understanding Inaccurate, and resulting in incorrect solutions, in order to further clarify this relationship, we may wish to write this paragraph as a formula: