Book:Euclid/The Elements/Book IV

Contents

 * Book IV: Circles: Inscription and Circumscription
 * Definitions
 * Proposition 1: Fitting a Chord Into a Circle
 * Proposition 2: Inscribing in Circle a Triangle Equiangular with Given
 * Proposition 3: Circumscribing about Circle a Triangle Equiangular with Given
 * Proposition 4: Inscribing a Circle in a Triangle
 * Proposition 5: Circumscribing a Circle about a Triangle
 * Proposition 6: Inscribing a Square in a Circle
 * Proposition 7: Circumscribing a Square about a Circle
 * Proposition 8: Inscribing a Circle in a Square‎
 * Proposition 9: Circumscribing a Circle about a Square
 * Proposition 10: Construction of Isosceles Triangle whose Base Angle is Twice Apex
 * Proposition 11: Inscribing a Regular Pentagon in a Circle
 * Proposition 12: Circumscribing a Regular Pentagon about a Circle
 * Proposition 13: Inscribing a Circle in a Regular Pentagon
 * Proposition 14: Circumscribing a Circle about a Regular Pentagon
 * Proposition 15: Inscribing a Regular Hexagon in a Circle
 * Proposition 16: Inscribing a Regular 15-gon in a Circle