Given :
L1:x−14=y−2−3=z−32 and
⇒D.R′s=(4,−3,2)
⇒D.C′s along L1=(l1,m1,n1)=(4√29,−3√29,2√29)
L2:x−13=y−24=z−3−2
⇒D.R′s=(3,4,−2)
⇒D.C′s along L2=(l2,m2,n2)=(3√29,4√29,−2√29)
If l1l2+m1m2+n1n2<0
Acute angle bisector is : x−x1l1−l2=y−y1m1−m2=z−z1n1−n2
Obtuse angle bisector is :
x−x1l1+l2=y−y1m1+m2=z−z1n1+n2
x1=1,y1=2,z1=3
So, equation is x−11/√29=y−2−7/√29=z−34/√29
⇒x−12=y−2−14=z−38⇒a=2,b=8