**Sol:**

**Steps of construction:**

Step 1: Draw a line segment XY of 12cm.

Step 2: Draw ∠DXY = ∠B = 45^{o} and ∠EYX = ∠C = 60^{o}

Step 3: Draw the angle bisectors of angles of DXY and EYX which intersects each other at A.

Step 4: Draw the perpendicular of AX and AY which intersect XY at B and C respectively.

Step 5: Join AB and AC

Therefore Δ ABC is the required triangle