习题教学是高中数学教学中的重要环节,我们在学习二倍角的三角函数时,一方面必须要注意其变形公式、另一方面我们要把握基本题型,即化简、求值、证明等问题,同时也要掌握提高型问题.我们需要首先必须学习、理解、牢固掌握二倍角公式.一、已知值求角给值求角的解决步骤是根据已知条件,选定所求角的一种三角函数值,并求出该三角函数值,根据条件判断出角的范围(一般将角的范围限定在相应三角 Exercises teaching is an important part of high school mathematics teaching. When we study trigonometric functions of double angle, on the one hand, we must pay attention to its deformation formula. On the other hand, we must grasp the basic questions such as simplifying, evaluating and proving , We must first learn, understand, and firmly grasp the double angle formula. First, the known value of the angle to the value of the angle-solving steps are based on known conditions, the selected angle Kind of trigonometric function value, and find the trigonometric function value, according to the conditions to determine the scope of the angle (usually the scope of the angle is limited to the corresponding triangle