plz. help me in constructing a triangle ABC where BC=6cm, AB=6cm median AD=4cm ???

Step 1:
Draw a rough sketch and mark the given measurements.

Step 2:
Draw BC = 6cm.
Step 3:
Bisect BC at D.
Step 4:
With B as centre and radius equal to 6cm, draw an arc x of a circle. With D as centre and radius equal to 4cm, draw an arc y to intersect the arc x at A.
Step 5:
Join AB and AC.

ABC is the required triangle.