So I am doing a write-up for a world setting set in our galaxy. I know the distance from Earth to the different stars in Light Years. However I am now trying to figure out how to measure the distance between these stars.

For instance distance between Alpha Lyrae and Delta Pavonis; for reference Delta Pavonis is 19.22 Light Years away from Earth. While Alpha Lyrae is 25.30 Light Years away.

I am no astronomer, so I hope the community here can give me some answers.