POINT • POINT • CIRCLE
Download GeoGebra file
Download GeoGebra file
Both Points In A Circle, One Is The Centre
Number of solutions: 2
GeoGebra construction
Steps
- Given is the circle c, inside of which lie the points A and B. A lies in the centre of c
- Construct the perpendicular bisector of AB, f. The resulting circles' origins will lie on it.
- Construct a line parallel to f that goes through the point B, g. The points where g intersects c shall be named C and D
- Construct the perpendicular bisectors of BC (h) and BD (i). The points where they intersect f shall be named F and E, respectively.
- Draw the circles d and e: d has E as its origin, goes through the points A and B, the point of tangency with c is D e has F as its origin, goes through the points A and B, the point of tangency with c is C
GeoGebra construction
Steps
- Solve for the circle k and two points A and B, one of which lies inside the circle and the other is its centre.
- Project the point inside the circle using circular inversion outside the circle.
- Draw tangents to the circle k passing through the projected point.
- Using circular inversion on the circle k, project the two tangents inside the circle. The circles k1 and k2 shown are solutions to the problem.