Angles and polygons
A handful of angle facts (straight lines , points , triangles , and the three parallel-line pairs) solve almost every angle problem. For polygons, start with the exterior angles: they always add up to .
≈ 30 minCircle theorems
Eight short theorems describe how angles behave in a circle. Learn each one with its exact wording, spot which one a diagram is using, and give it as your reason.
≈ 35 minSimilarity and congruence
Similar shapes are enlargements of each other: same angles, all lengths multiplied by the same scale factor . Areas then scale by and volumes by . Congruent shapes are identical: .
≈ 30 minBearings, scale drawings and symmetry
A bearing is an angle measured clockwise from north, written with three figures. To reverse a bearing, add or subtract . Map scales turn real distances into drawn ones, and symmetry describes how a shape fits onto itself.
≈ 25 minConstructions and loci
A locus is the set of all points that obey a rule. Points a fixed distance from a point make a circle; equidistant from two points, the perpendicular bisector; equidistant from two lines, the angle bisector. Ruler-and-compass constructions draw these exactly, and you leave the arcs to show your method.
≈ 30 min