Let A=1,2,3. Consider the relation R=(1,1),(2,2), (3,3), (1,2),(2,3),…

$A=\{1,2,3\}$

all $(1,1),(2,2), (3,3)∈R$ ⇒ R is reflexive

for $(1,2)∈R(2,1)∉R$ ⇒ R is not symmetric

for $(1,2)∈R,(2,3)∈R,(1,3)∈R$ ⇒ R is transitive