Geometric notation and conventions

OCR J560 expects students to read and use standard geometric notation across all six papers. Marks are routinely awarded B1 for correct labelling of diagrams, even before any calculation begins. Get the language right and the geometry questions become easier to parse.

Points, lines and planes

• A point has position but no size. Labelled with a single capital letter (A, B, C…).
• A line is a straight 1D object extending infinitely. The line through points A and B is written AB (with an over-bar or just AB in OCR papers). The line segment AB is the bit between A and B.
• A ray AB starts at A and passes through B, extending infinitely beyond B.
• A plane is a flat 2D surface. In 3D problems OCR may refer to the "plane ABC" — the unique flat surface through three non-collinear points.

Angles

• An angle is measured in degrees (°). Right angle = 90°, straight angle = 180°, full turn = 360°.
• Angle ABC means the angle at vertex B with rays going to A and C. The middle letter is the vertex.
• Acute < 90°; right = 90°; obtuse 90°–180°; reflex 180°–360°.

Polygons

A polygon is named by its number of sides: triangle (3), quadrilateral (4), pentagon (5), hexagon (6), heptagon (7), octagon (8), nonagon (9), decagon (10). Regular polygons have all sides AND all angles equal.

Vertex, edge, face

For 3D solids:

• Vertex (vertices): a corner where edges meet.
• Edge: a straight line where two faces meet.
• Face: a flat surface of the solid.

Euler's formula for convex polyhedra: V − E + F = 2.

Parallel and perpendicular notation

• Parallel lines: AB ∥ CD (the lines never meet).
• Perpendicular lines: AB ⊥ CD (meet at 90°).
• On diagrams, parallel lines are marked with single arrows (or double, etc.); right angles are marked with a small square.

Equal lengths and angles on diagrams

• Equal sides shown by tick marks (single tick, double tick…).
• Equal angles shown by matching arcs.

OCR examiner phrasing

OCR mark schemes credit B1 for correct identification of features (e.g. "isosceles" or "alternate angles"). Always state the geometric reason in words; numerical answers without justification often lose A1 in "show that" or "prove" questions.