To verify the constant of a particular prism, a straight line ABC is laid out. The EDM instrument is first set up at A, with the following measurements recorded:
![2171_0709bf0b-3cee-41b6-820d-b2784bad1c0f.png](https://secure.tutorsglobe.com/CMSImages/2171_0709bf0b-3cee-41b6-820d-b2784bad1c0f.png)
The EDM instrument is then set up at B, where distance BC is recorded as 289.595 m. Determine the prism constant.