how do you show that A⇒B is equivalent to (NOT A) OR B?

i tried but i cant get the answer

A B NOT A A⇒B (NOT A) OR B

T F F T F

T F F F T

F T T T T

F F T T F

this is in the format of a table where the first row is the heading and the subsequent rows are cases when A and B and TRUE and FALSE.

i tried to prove ti as seen above but im not able to show that they are equivalent. someone please help..

Thanks!