Co-ordinate

slope of AB= difference of y coordinates/ difference of x coordinates=8-0/0-6=-4/3

OP is perpendicular from O to AB.

sO,

 SLOPE OF op=-1/ slope of AB=3/4

So, equation of OP can be found using pointO(0,00 and slope 3/4

 as

 y-0=3/4(x-0)

So,

 4y=3x

 or 3x=4y is the required equation.