Geometry Basics
Understand shapes, angles, and measurements
Geometry Fundamentals
Geometry is the study of shapes, sizes, and properties of figures and spaces.
Basic Concepts
Point: A location with no size or shape
Line: Extends infinitely in both directions
Line Segment: Part of a line with two endpoints
Angle: Formed by two rays with a common endpoint, measured in degrees
Types of Angles
- Acute: Less than 90°
- Right: Exactly 90°
- Obtuse: Between 90° and 180°
- Straight: Exactly 180°
Triangles
Types by sides: Equilateral (all equal), Isosceles (two equal), Scalene (all different)
Types by angles: Acute, Right, Obtuse
Triangle Sum Theorem: All angles sum to 180°
Area: A = ½ × base × height
Quadrilaterals
Square: All sides equal, all angles 90°. Area = side²
Rectangle: Opposite sides equal, all angles 90°. Area = length × width
Parallelogram: Opposite sides equal and parallel. Area = base × height
Trapezoid: One pair of parallel sides
Circles
Radius (r): Distance from center to circumference
Diameter (d): d = 2r
Circumference: C = 2πr = πd
Area: A = πr²