You may be asked to show that two circles are touching, and say whether they're touching internally or externally. To do this, you need to work out the radius and the centre of each circle. If the sum ...

Two intersecting lines are tangent to two circles and form an angle of 74°. The circles have area ratios of 36 to 25. The distance from the point of tangency on the large circle to the point of ...

Summary We prove the next generalization of the Steiner-Lehmus theorem: if two equal cevians intersect with each other on the angle bisector of the third triangle vertex, then the triangle is ...