Angle Puzzles & Decomposing Angles
Angles are all around us. Use the protractor to measure, drag a ray to split angles into two parts, and solve puzzles to find the missing angle.
Choose a mode
60°Acute
60° is less than 90° - it is an acute angle
Try a preset angle
Angle Reference
Types of Angles
- Acute: less than 90°
- Right: exactly 90° (square corner)
- Obtuse: between 90° and 180°
- Straight: exactly 180° (flat line)
- Reflex: more than 180°
- Full turn: 360°
Angles Are Additive
You can split any angle into smaller parts and add them back up.
- 30° + 60° = 90° (right angle)
- 55° + 125° = 180° (straight angle)
- Angles on a straight line always sum to 180°
- Angles around a point always sum to 360°
Related Content
Visual Explainers
Related Tools
Area & Perimeter Explorer
Calculate area and perimeter of rectangles, triangles, parallelograms, trapezoids, and circles with SVG visuals and step-by-step formulas.
Angle Relationships Explorer
Visualize complementary, supplementary, vertical angles, and parallel lines with transversals. Color-coded equal angle pairs.
Compass & Straightedge Explorer
Explore 15 classical geometry constructions step by step. Watch animations, drag points, and try constructions yourself.
Conic Sections Explorer
Explore circles, ellipses, parabolas, and hyperbolas with interactive graphs, equations, foci, and tangent lines.
Related Labs
Angle Builder Lab
Build angles from 0° to 360° using a slider, classify each as acute, right, obtuse, straight, or reflex, and record data to discover the boundaries between angle types and the landmark turn angles.
Shape Detective & Angle Hunt Lab
Hunt for angles in 8 different shapes. Classify each angle as acute, right, obtuse, or straight, then identify what type of triangle or quadrilateral each shape is.
Shape Classifier Lab
Explore 12 geometric shapes from triangles to circles. Inspect sides, angles, parallel pairs, and lines of symmetry for each shape, then record your findings to discover the properties that define each shape family.
Symmetry & Pattern Blocks Lab
Investigate lines of symmetry in 10 shapes. Toggle vertical, horizontal, and diagonal fold lines to discover which shapes have the most symmetry, then record your findings and look for patterns across regular and irregular shapes.
