锐角三角函数值的求解一般需将锐角放到直角三角形中根据定义进行求解,具体求解时需要具体情况具体分析,下面举例加以说明.一、直接求解法当角已在直角三角形中时,可直接应用锐角三角函数定义求解.例1(2011年江苏苏州)如图1,在四边形ABCD中,E、F分别是AB、AD的中点,若EF=2,BC=5,CD=3,则tanC等于(). The solution of the acute trigonometric function value generally need to be solved by the definition of the acute angle into the right triangle, the specific solution needs specific analysis, the following example to illustrate.First, the direct solution method When the angle is in the right triangle, can be directly Example 1 (Suzhou, Jiangsu Province, 2011) As shown in Figure 1, in the quadrilateral ABCD, E and F are the midpoints of AB and AD respectively. If EF = 2, BC = 5 and CD = 3, tanC is equal to ().