3 Geometry and trigonometry
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3.1 Geometry and trigonometry - SL content
SL 3.1Three-dimensional geometry
• Use distance and midpoint in three-dimensional space. • Use volume and surface area of 3D solids and combinations. • Identify right-angled triangles in 3D objects to find lengths and angles.
SL 3.2Triangle trigonometry
• Use sine, cosine and tangent in right-angled triangles. • Use sine rule, cosine rule and area formula 1/2 ab sin C. • Ambiguous sine-rule case is not included at SL.
SL 3.3Applications of trigonometry
• Apply right and non-right triangle trigonometry, including Pythagoras' theorem. • Use elevation/depression, bearings and labelled diagrams from written statements.
SL 3.4Arc length and sector area
• Find circle arc length and sector area. • Radians are not required at SL.
SL 3.5Perpendicular bisectors
• Find equations of perpendicular bisectors. • Use two points, or a line segment equation and midpoint.
SL 3.6Voronoi diagrams
• Use sites, vertices, edges and cells in Voronoi diagrams. • Add a site, use nearest-neighbour interpolation and solve toxic-waste-dump style problems. • Find boundaries, closest sites and region areas; applications include planning, disease, ecology and meteorology.
3.2 Geometry and trigonometry - AHL content
AHL 3.7 (HL)—Radian measure
• Define radians and convert between degrees and radians. • Use radians for arc length and sector area.
AHL 3.8 (HL)—Unit circle and trigonometric equations
• Define sin theta and cos theta using the unit circle; tan theta=sin theta/cos theta. • Use cos^2 theta + sin^2 theta = 1 and ambiguous sine-rule case. • Construct sin x and cos x graphs from the unit circle; solve trig equations graphically on finite intervals.
AHL 3.9 (HL)—Matrix transformations and fractals
• Use matrices for 2D transformations: reflections, stretches, enlargements, translations and rotations. • Compose transformations and interpret determinant as area scale factor. • Use iterative techniques to generate fractals.
AHL 3.10 (HL)—Vectors
• Use vectors/scalars, directed line segments, unit vectors and base vectors i, j, k. • Use components, column representation, vector algebra, magnitude, normalization and resultants.
AHL 3.11 (HL)—Vector equations of lines
• Use vector equation r=a+lambda b in 2D and 3D. • Convert vector line equations to parametric form.
AHL 3.12 (HL)—Vector kinematics
• Model constant-velocity linear motion in 2D/3D with r=r0+vt. • Find positions, intersections, paths, closest approach times and distances. • Include variable velocity in 2D; projectile and circular motion are special cases.
AHL 3.13 (HL)—Scalar and vector products
• Use scalar product to find angles and test perpendicular vectors. • Use vector product, right-hand rule and |v x w| for parallelogram/triangle area. • Resolve components parallel and perpendicular to another vector.
AHL 3.14 (HL)—Graph theory basics
• Use graph terminology: vertices, edges, adjacent items, degree, simple/complete/weighted graphs. • Represent real-world structures as weighted or unweighted graphs. • Know connected, strongly connected, directed graphs, in/out degree, subgraphs and trees.
AHL 3.15 (HL)—Adjacency matrices and transition matrices
• Use adjacency matrices to count k-length walks using powers of a matrix. • Use weighted adjacency tables. • Construct transition matrices for strongly connected directed/undirected graphs.
AHL 3.16 (HL)—Graph algorithms
• Use walks, trails, paths, circuits, cycles, Eulerian trails/circuits and Hamiltonian paths/cycles. • Use Kruskal's and Prim's algorithms for minimum spanning trees. • Solve Chinese postman problems for weighted graphs with up to four odd vertices. • Use nearest-neighbour and deleted-vertex algorithms for travelling salesman bounds.