1. Draw a  ray  bx  and cut of a line segment =6 cm from it
2. Construct angle XBY=45%
3. from by   cut of line segment BD=12 cm
4. Join CD
5.Draw a perpendicular bisector of CD intersecting BY at point A
6. join AC 
7.ABC is a required  tiangle

1 4 1
if you want i can send the figure
please mark as braniest
in question <B = 60 not 45
ok you take it as 60