This subsection contains the propositions from Book 6 of Euclid's “Elements”.

- Proposition: 6.01: Areas of Triangles and Parallelograms Proportional to Base
- Proposition: 6.02: Parallel Line in Triangle Cuts Sides Proportionally
- Proposition: 6.03: Angle Bisector Theorem
- Proposition: 6.04: Equiangular Triangles are Similar
- Proposition: 6.05: Triangles with Proportional Sides are Similar
- Proposition: 6.06: Triangles with One Equal Angle and Two Sides Proportional are Similar
- Proposition: 6.07: Triangles with One Equal Angle and Two Other Sides Proportional are Similar
- Proposition: 6.08: Perpendicular in Right-Angled Triangle makes two Similar Triangles
- Proposition: 6.09: Construction of Part of Line
- Proposition: 6.10: Construction of Similarly Cut Straight Line
- Proposition: 6.11: Construction of Segment in Squared Ratio
- Proposition: 6.12: Construction of Fourth Proportional Straight Line
- Proposition: 6.13: Construction of Mean Proportional
- Proposition: 6.14: Characterization of Congruent Parallelograms
- Proposition: 6.15: Characterization of Congruent Triangles
- Proposition: 6.16: Rectangles Contained by Proportional Straight Lines
- Proposition: 6.17: Rectangles Contained by Three Proportional Straight Lines
- Proposition: 6.18: Construction of Similar Polygon
- Proposition: 6.19: Ratio of Areas of Similar Triangles
- Proposition: 6.20: Similar Polygons are Composed of Similar Triangles
- Proposition: 6.21: Similarity of Polygons is Transitive
- Proposition: 6.22: Similar Figures on Proportional Straight Lines
- Proposition: 6.23: Ratio of Areas of Equiangular Parallelograms
- Proposition: 6.24: Parallelograms About Diameter are Similar
- Proposition: 6.25: Construction of Figure Similar to One and Equal to Another
- Proposition: 6.26: Parallelogram Similar and in Same Angle has Same Diameter
- Proposition: 6.27: Similar Parallelogram on Half a Straight Line
- Proposition: 6.28: Construction of Parallelogram Equal to Given Figure Less a Parallelogram
- Proposition: 6.29: Construction of Parallelogram Equal to Given Figure Exceeding a Parallelogram
- Proposition: 6.30: Construction of the Inverse Golden Section
- Proposition: 6.31: Similar Figures on Sides of Right-Angled Triangle
- Proposition: 6.32: Triangles with Two Sides Parallel and Equal
- Proposition: 6.33: Angles in Circles have Same Ratio as Arcs