This subsection contains the propositions from Book 11 of Euclid's “Elements”.

- Proposition: Prop. 11.01: Straight Line cannot be in Two Planes
- Proposition: 11.02: Two Intersecting Straight Lines are in One Plane
- Proposition: Prop. 11.03: Common Section of Two Planes is Straight Line
- Proposition: Prop. 11.04: Line Perpendicular to Two Intersecting Lines is Perpendicular to their Plane
- Proposition: Prop. 11.05: Three Intersecting Lines Perpendicular to Another Line are in One Plane
- Proposition: Prop. 11.06: Two Lines Perpendicular to Same Plane are Parallel
- Proposition: Prop. 11.07: Line joining Points on Parallel Lines is in Same Plane
- Proposition: Prop. 11.08: Line Parallel to Perpendicular Line to Plane is Perpendicular to Same Plane
- Proposition: Prop. 11.09: Lines Parallel to Same Line not in Same Plane are Parallel to each other
- Proposition: Prop. 11.10: Two Lines Meeting which are Parallel to Two Other Lines Meeting contain Equal Angles
- Proposition: Prop. 11.11: Construction of Straight Line Perpendicular to Plane from point not on Plane
- Proposition: Prop. 11.12: Construction of Straight Line Perpendicular to Plane from point on Plane
- Proposition: Prop. 11.13: Straight Line Perpendicular to Plane from Point is Unique
- Proposition: Prop. 11.14: Planes Perpendicular to same Straight Line are Parallel
- Proposition: Prop. 11.15: Planes through Parallel Pairs of Meeting Lines are Parallel
- Proposition: Prop. 11.16: Common Sections of Parallel Planes with other Plane are Parallel
- Proposition: Prop. 11.17: Straight Lines cut in Same Ratio by Parallel Planes
- Proposition: Prop. 11.18: Plane through Straight Line Perpendicular to other Plane is Perpendicular to that Plane
- Proposition: Prop. 11.19: Common Section of Planes Perpendicular to other Plane is Perpendicular to that Plane
- Proposition: Prop. 11.20: Sum of Two Angles of Three containing Solid Angle is Greater than Other Angle
- Proposition: Prop. 11.21: Solid Angle contained by Plane Angles is Less than Four Right Angles
- Proposition: Prop. 11.22: Extremities of Line Segments containing three Plane Angles any Two of which are Greater than Other form Triangle
- Proposition: Prop. 11.23: Sum of Plane Angles Used to Construct a Solid Angle is Less Than Four Right Angles
- Proposition: Prop. 11.24: Opposite Planes of Solid contained by Parallel Planes are Equal Parallelograms
- Proposition: Prop. 11.25: Parallelepiped cut by Plane Parallel to Opposite Planes
- Proposition: Prop. 11.26: Construction of Solid Angle equal to Given Solid Angle
- Proposition: Prop. 11.27: Construction of Parallelepiped Similar to Given Parallelepiped
- Proposition: Prop. 11.28: Parallelepiped cut by Plane through Diagonals of Opposite Planes is Bisected
- Proposition: Prop. 11.29: Parallelepipeds on Same Base and Same Height whose Extremities are on Same Lines are Equal in Volume
- Proposition: Prop. 11.30: Parallelepipeds on Same Base and Same Height whose Extremities are not on Same Lines are Equal in Volume
- Proposition: Prop. 11.31: Parallelepipeds on Equal Bases and Same Height are Equal in Volume
- Proposition: Prop. 11.32: Parallelepipeds of Same Height have Volume Proportional to Bases
- Proposition: Prop. 11.33: Volumes of Similar Parallelepipeds are in Triplicate Ratio to Length of Corresponding Sides
- Proposition: Prop. 11.34: Parallelepipeds are of Equal Volume iff Bases are in Reciprocal Proportion to Heights
- Proposition: Prop. 11.35: Condition for Equal Angles contained by Elevated Straight Lines from Plane Angles
- Proposition: Prop. 11.36: Parallelepiped formed from Three Proportional Lines equal to Equilateral Parallelepiped with Equal Angles to it forme
- Proposition: Prop. 11.37: Four Straight Lines are Proportional iff Similar Parallelepipeds formed on them are Proportional
- Proposition: Prop. 11.38: Common Section of Bisecting Planes of Cube Bisect and are Bisected by Diagonal of Cube
- Proposition: Prop. 11.39: Prisms of Equal Height with Parallelogram and Triangle as Base