3D Geometry: Solids & Sections

Solid geometry is hard when you can't picture it. 3D Geometry turns textbook diagrams into 3D models you can rotate, slice and unfold, and gives every length, area and volume as an exact value like 2√2 or 12π.

Free to download: the core 3D models, formulas and unfolding animations are free, and every Pro tool can be tried in full once before you decide.

FREE FEATURES
• 9 solids: cube, cuboid, regular tetrahedron, square pyramid, triangular prism, cylinder, cone, sphere, torus
• Textbook labeling (ABCD-A₁B₁C₁D₁); hidden edges turn dashed automatically from any angle
• Formulas with exact answers: surface area, volume, diagonals, slant height and more
• Unfolding animations: cubes, prisms and pyramids open step by step; a cone unrolls into a sector; a sphere is approximated by orange-peel gores

PRO PROBLEM-SOLVING TOOLS
• Cross-sections: drag a cutting plane and see the section's shape and area in real time. Reproduce the triangle, rhombus, pentagon and regular hexagon sections of a cube, or slice a cone to get an ellipse, parabola and hyperbola
• Angles and distances in space: tap points in 3D to get the angle between skew lines, line–plane angle, dihedral angle, point-to-plane distance and distance between skew lines, with the translated line, projection or common perpendicular drawn for you
• Circumscribed and inscribed spheres: center, radius and derivation steps, all visualized
• Shortest paths: the classic "ant on a box" problem with three unfoldings compared; unroll a cylinder or cone to turn the curved path into a straight line
• Cube nets: folding animations for all 11 nets, opposite faces color-matched, common trick shapes, and a random "will it fold?" quiz
• Three views: front, side and top orthographic views in standard layout, with hidden edges dashed
• 24 worked exam-style problems: hint, answer, then step-by-step solution, each opening in 3D so you can explore it yourself
• Classroom mode: full-screen presentation, whiteboard background, pen annotations, and export to high-resolution images and GIF animations for slides

ONE-TIME PURCHASE, NO SUBSCRIPTION
Pro is a single in-app purchase that unlocks everything on iPhone, iPad and Mac.

WHO IT'S FOR
• Middle school students: nets, shortest paths, three views
• High school students: cross-sections, circumscribed spheres, angles and distances in space
• Math teachers: demonstrate on a projector, annotate, and export animations for lessons

Note: the in-app text is currently in Chinese. The 3D models, labels and math notation work in any language.