If A=5i-6j and B= -2i+3j and c lies in the xy plane is perpendicular to A if C.B=9.
C vector lies in xy plane. so, let C=xi + yj.
C vector is perpendicular to A vector. so, C.A=0
(xi + yj).(5i-6j)=0
5x -6y=0 (1)
C.B=9
(xi +yj).(-2i+3j)=9
-2x+3y=0 (2)
by solving (1),(2)
x=18.
y=15.
Vector C=18i+15j.
