Is Rita justified in hiding from Denny the fact that she is still on the pill? Why or why not?

This question seems to be incomplete. However, there is enough information to find the right answer.

Yes

Explanation:

First of all, is every woman´s right to be able to freely choose whether or not she wants to use any method of contraception, something that was already established in the 1980s, the time setting of the play "Educating Rita" (1980), by Willy Russell.

However, even without that in mind, Rita´s secrecy about her taking the pill was due to her husband´s pressure over her to become pregnant despite her not feeling ready. Having a child would have become an obstacle on her academic path, and she knew it. Denny not only became violent when he found out but even make her choose between getting off the pill or moving out. Luckily, Rita left him to continue her studies.

is there an image you meant to add?

explanation:

it is the background information on the characters and setting explained at the beginning of the story. the exposition will often have information about events that happened before the story began. the exposition is often the very first part of the plot.