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二倍角是继三角函数的诱导公式和两角和与差的正弦、余弦、正切公式之后的又一重要公式,它为今后研究三角恒等式及三角函数等问题提供了又一必备的工具。因此它起着承上启下的作用。同时,也是培养学生逻辑思维能力和化归的重要数学思想方法。本文主要研究二倍角公式的推导、变形及应用,并利用二倍角公式进行三角的求值、化简,同时能理解由特殊到一般的化归数学思想方法。
The double angle is another important formula following the trigonometric function’s induction formula and the two-angle and difference sine, cosine and tangent formulas. It provides an indispensable tool for further research on trigonometric functions and trigonometric functions. So it plays the role of link. At the same time, it is also an important mathematical thinking method of cultivating students’ logical thinking ability and returning to normal. In this paper, we mainly study the derivation, deformation and application of the double angle formula, and use the double angle formula to evaluate and simplify trigonometry. At the same time, we can understand the specialization-to-generalized mathematical thinking method.