How to get the public key of an SSL certificate, having the certificate itself and the private key?

Question

Digital certificates

Good afternoon!
There is hosting, with the ability to automatically install a free certificate from letsencrypt. I myself am not well versed in generating certificates, how many times I have not tried to create them .. Therefore, I took advantage of this opportunity from the hoster.
After installation in the hosting panel, I see
-----BEGIN RSA PRIVATE KEY-----
...
-----BEGIN CERTIFICATE-----
...
And I need to get the public key of this certificate. Support in the chat replied "use them to get a private key".
Tell me how can I do this?

Answer 1

Isn't the feature of LE just that he does everything himself, without requiring the user to have knowledge of certificates?
JFYI: The one below the BEGIN CERTIFICATE text is the public key, also known as the certificate.

Answer 2

For letsencrypt to work, a private certificate and the certificate itself, which is essentially the public key, are sufficient))

Answer 3

The public key is part of the certificate.
For this, a certificate is needed - to tell others: trust this public key, and you will be happy.