To find equation of BC, first we will find coordinates of B and C.

mAC=23
AC and BB′ are perpendicular to each other
hence mBB′=−32
Equation of line passing through (x1,y1) and having slope m is y−y1=m(x−x1)
For equation of BB′
y−1=3−2(x−1)
⇒2x+3y=5........(1)
Point of intersection of AB and BB′ ⇒B(235,−10)
Similarly point C(−13,−233)
Equation of BC is, y−y1=x2−x1y2−y1(x−x1)
y+10=6113(x−235)
∴26x−122y−1675=0