Revision GuideGeometry & Trigonometry
Geometry Formula Reference Pack
A richer geometry reference pack covering area, perimeter, circles, and triangle methods with unit reminders and method-selection guidance.
Printable PDFOpen download
Worked Examples PackGeometry & Trigonometry
Triangles and Angles Worked Examples Pack
A more useful worked-examples pack for triangle methods, hypotenuse calculations, and degree-radian relationships.
Filename: triangles-and-angles-worked-examples-pack.pdfFile size: 3 KB
Formula highlights
Triangle area
A = 1/2 x base x height
Degrees to radians
radians = degrees x pi / 180
Triangle example set
Right triangle with legs 6 and 8 -> hypotenuse 10.
Triangle with base 12 and height 5 -> area 30 square units.
Triangle with sides 13, 14, 15 -> area 84 square units using Heron’s formula.
Angle conversion examples
45 degrees = pi/4 radians.
120 degrees = 2pi/3 radians.
1 radian is about 57.3 degrees.
Method-choice reminders
- Use Pythagoras only for right triangles.
- Use base-height area when a perpendicular height is known.
- Use Heron’s formula when all three side lengths are known.
Common mistakes
- Misidentifying the hypotenuse.
- Using a non-perpendicular side as height.
- Switching calculator angle modes without noticing.
Related calculators
Use the formulas in live tools.
Right Triangle Hypotenuse Calculator
Use the Right Triangle Hypotenuse Calculator to calculate right triangle hypotenuse from the measurements you enter, with clear formulas and consistent units.
Geometry & TrigonometryOpen
Triangle Area Calculator
Use the Triangle Area Calculator to calculate triangle area from the measurements you enter, with clear formulas and consistent units.
Geometry & TrigonometryOpen
Heron Triangle Area Calculator
Use the Heron Triangle Area Calculator to calculate heron triangle area from the measurements you enter, with clear formulas and consistent units.
Geometry & TrigonometryOpen
Degrees to Radians Calculator
Use the Degrees to Radians Calculator to calculate degrees to radians from the measurements you enter, with clear formulas and consistent units.
Geometry & TrigonometryOpen
Radians to Degrees Calculator
Use the Radians to Degrees Calculator to calculate radians to degrees from the measurements you enter, with clear formulas and consistent units.
Geometry & TrigonometryOpen
More downloads
Continue the topic cluster.
Guide cluster
Related reading around the same topic.
Geometry & TrigonometryFlagship guide
Triangle Methods
A stronger guide to right-triangle relationships, triangle area methods, and Heron’s formula, with emphasis on choosing the method that matches the information you actually have.
Students and practical users who meet triangle geometry in surveying, construction, trigonometry preparation, and coordinate problems.Read guide
Geometry & Trigonometry
Angles and Radians
A more complete guide to degrees and radians, including why radians are natural in higher maths and physics, how to convert cleanly, and when each unit is preferred.
Students and technical users moving between everyday angle language and the radian-based formulas common in calculus, trigonometry, and engineering.Read guide