AC的平方=AB乘以AD ==>> AC:AB=AD:AC ==>>ΔABC与ΔACD相似
==>> AD=CD =>∠A=∠ACD=36 (又AC=BC ∠A=∠B=36) ==>>∠BCD=∠BDC ==>> BC=BD
设AD=x, AB=1 => BD=1-x=BC=AC
由AC的平方=AB乘以AD 列方程
(1-x)^2=x ==>> x=(3-根号5)/2 或 (3+根号5)/2>1(舍去)
AC=1-x= [(根号5)-1]/2
AC的平方=AB乘以AD ==>> AC:AB=AD:AC ==>>ΔABC与ΔACD相似
==>> AD=CD =>∠A=∠ACD=36 (又AC=BC ∠A=∠B=36) ==>>∠BCD=∠BDC ==>> BC=BD
设AD=x, AB=1 => BD=1-x=BC=AC
由AC的平方=AB乘以AD 列方程
(1-x)^2=x ==>> x=(3-根号5)/2 或 (3+根号5)/2>1(舍去)
AC=1-x= [(根号5)-1]/2