# The Vector Geometry Tool: Computing the Intersection Between a Line and a Circle

Given: Two known lat/lon points (a, b) and a circle centered on the 2nd point with known radius. Solve for the lat/lon of a point (a') where the line intersects the circle.

## Solution Steps

1. First turn off all terrain. ​
2. Create two target objects at Point A and Point B with 0 km altitude and LOS constraint disabled on both target objects. 3. Create an ellipse area target of semimajor axis = semiminor axis = known distance r with Centroid at Point B. 4. Create a displacement type vector between Target A and Target B. 5. Run an AER report between the targets with reference point being the circle origin target.​ 6. Create a Fixed in System type Point of Spherical Fixed Point type with Right Ascension = Azimuth angle and Declination = 0 - Elevation angle (where Azimuth and Elevation are from AER report) and Magnitude = r.​ 7. Report on Latitude and Longitude using Data Provider = Points(Fixed) - Detic Latitude and Points(Fixed) - Detic Longitude ​ Posted: 4/25/2016 11:00:47 AM