在同角三角函数的关系中,“切割化弦”是解决三角题的通法,但它的反面:“弦化切”则很少用,其实在学习中,要重视一个事物的两面,不要过于强调一面,偏废另一面.本文就想说明“弦化切”在解一些三角题时也有它的妙处. 例1 若sin2x>cos2x,则x的取值范围是 In the relationship of the same-angle trigonometric function, “cutting the string” is a common method to solve the trigonometric problem, but its opposite: “string-cutting” is rarely used. In fact, in learning, we must pay attention to both sides of a thing. Too much emphasis on one side, but on the other side. This article would like to explain that “string cut” also has its advantages when solving some trigonometric problems. Example 1 If sin2x>cos2x, then the value range of x is