在实际问题中,我们经常会遇到斜三角形的问题,这时可通过“割”或“补”的方法,将斜三角形恰当地转化为直角三角形进行解答.例1如图1,在△ABC中,∠A=30°,tan B=3~(1/2)/2,AC=23~(1/2),求AB的长.分析∠A=30°,由tan B=3~(1/2)/2知,∠B不是特殊角,故可知△ABC不是直角三角形.而欲求AB的长,需用到AC、∠A和tan B,因此,需构造直角三角形把∠A、∠B化为直角三角形中的角,然后运用各元素之间的关系求解.解如图1,过点C作CD⊥AB,垂足为D.在Rt△ABC中, In practical problems, we often encounter the problem of oblique triangle, this time by “cut ” or “fill ” method, the oblique triangle will be properly converted into a right triangle to answer .Example 1 shown in Figure 1 In ABC, 长A = 30 °, tan B = 3 ~ (1/2) / 2, AC = 23 ~ (1/2) = 3 ~ (1/2) / 2, ∠B is not a special angle, so we can see that △ ABC is not a right triangle, but for the length of AB, AC, ∠A and tan B are needed. Therefore, ∠A, ∠B into the angle of the right triangle, and then use the relationship between the elements of solution. Solution shown in Figure 1, over point C for CD ⊥ AB, foot drop is D. In Rt △ ABC,