Geometry - Lines, Angles, Shapes

Lines & Angles: • Point: No dimension, exact location • Line: Extends infinitely in both directions • Ray: Has one endpoint, extends infinitely • Angle types: Acute (<90°), Right (=90°), Obtuse (>90°), Straight (=180°)

Triangles: • Sum of angles = 180° • Types: Equilateral (all equal), Isosceles (2 equal), Scalene (all different) • Area = ½ × base × height

Quadrilaterals: • Rectangle: Opposite sides equal, all angles 90° • Square: All sides equal, all angles 90° • Parallelogram: Opposite sides parallel

Circles: • Radius (r): Distance from center to edge • Diameter (d): 2 × radius • Circumference: 2πr or πd • Area: πr²