Let BD=DA=a, use cosine theorem to get AC 2 = 5 2+A 2-2A * 5cos angle ADC, and use cosine theorem to get BC 2 = 5 2+A 2-2A * 5cos angle BDC in triangle BDC, angle ADC+ angle BDC= 180.

Triangle ABC is an RT triangle with angle BCA=90 degrees. According to Pythagorean theorem, AC 2+BC 2 = AB 2 = 4A 2;

It can be concluded that a=5, that is, BD=DA=CD=5,

If the intersection D is the perpendicular of AC and the vertical foot is E, then DE//BC, and D is the midpoint of AB, and DE=BC/2=4. In the triangle CDE, CD = 5 and DE = 4, then CE=3.

Sin angle ACD=sin angle ECD=4/5, cos angle ACD=cos angle ECD=3/5, tan angle ACD=tan angle ECD=4/3.