How to calculate the distance between stars

What the upstairs two are talking about is to determine the distance between the celestial body and the earth by using the triangular parallax method, and to obtain it by using the annual parallax and trigonometric function. Cepheid variable stars, cluster method is also distance measurement.

The landlord asked if two celestial bodies are on the same plane, their spatial distance.

Sorry, landlord, I haven't given you an answer these days.

After consideration, I think the method I originally proposed is still feasible, which can be obtained by measuring the angular distance, but this method can only get the distance ratio between these two stars and those two stars, and can't get the exact data.

I will send you a new message.