Question

在直角三角形ABC中,角ACB=90度,CD垂直AB于D,AC=3,AB=5,则AD等于

在直角三角形ABC中,角ACB=90度,CD垂直AB于D,AC=3,AB=5,则AD等于我要过程

Answer 1

解：∵∠ACD=∠B（同角的余角相等），而∠A为公共角∴Rt△ACD∽Rt△ABC∴AC/AB=AD/AC∴AD=AC�0�5/AB=9/5

Answer 2

△ACB与△ADC中∠CAB=∠DAC∠ACB=∠ADC∴△ACB∽△ADCAC/AD=AB/ACAD=AC^2/AB=9/5

Answer 3

AB^2=AC^2+BC^2 =25AB=5AC*BC=AB*CD所以CD=2.4

Answer 4

=于4