EF ( x1=0, y1=1), (x2=3, y2=3)
JK (x1=8, y1=2), (x2=6, y2=5)
Slope of a line=(y2-y1)/(x2-x1)
Slope of EF =( 3-1)/(3-0)= 2/3
Slope of JK =(5-2)/(6-8)= 3/-2
Since the slopes of those lines are negative reciprocal the lines are perpendicular
Line EF is perpendicular to JK