所谓倍角三角形,就是三角形的一个内角是另一个内角的2倍的三角形．这种三角形有几条重要性质,本文举例分析,以便于同学们加深对这部分知识的理解．轻松应对这类题．例题在ΔABC中,∠A,∠B,∠C所对的边分别用a,b,c表示．(1)如图1,在ΔABC中,∠A=2∠B,且∠A=60°,求证：a~2=b(b+c)． The so-called double-angled triangle is a triangle whose internal angle is 2 times that of another internal angle. This kind of triangle has several important properties. This article gives an example analysis to facilitate the students to deepen their understanding of this part of the knowledge. Easily deal with such questions. In the case of ΔABC, the edges of ∠A, ∠B, ∠C are denoted by a, b, c respectively. (1) In Figure 1, in ΔABC, ∠A=2∠B, and ∠A=60°, verify that: a~2=b(b+c).