Branch 05 · free, no sign-up
Geometry Calculators
Geometry is algebra with a picture attached. Each calculator names the theorem or formula it is using, so the answer is traceable back to a reason rather than a shape you had to recognise.
Every calculator in this branch is checked by a mathematician before it goes live.
- a² + b² = c² the Pythagorean theorem
- 6² + 8² = c² substitute the two legs
- 100 = c² 36 + 64
- c = 10 take the positive root — a length cannot be negative
Calculators
All 14 geometry calculators, by topic
flat shapes, then solids, then shapes on a grid
Plane Figures
Solids
Coordinate Geometry
Theorems
Where this sits
What comes before geometry
each topic assumes the one to its left
Stuck part way through? Start at the leftmost topic you are not sure about — everything to the right depends on it.
Knowledge base
Read the reasoning, not just the answer
one article per question a teacher would answer
Questions
Asked often enough to answer here
the ones that change how you work, not trivia
Does the Pythagorean theorem work on any triangle?
Only on right-angled ones. For other triangles you need the law of cosines, which is the same idea generalised — and which reduces to Pythagoras when the angle is 90°.
Why is area squared and volume cubed?
Because area multiplies two lengths and volume multiplies three. The unit records how many lengths went into the answer, which is also why doubling a side quadruples the area but multiplies the volume by eight.
Do I have to memorise every area formula?
No. Learn the rectangle and the triangle properly and most of the others follow: a parallelogram is a rearranged rectangle, a trapezium is two triangles.
Nearby
Branches that touch this one
linked because the maths overlaps, not because it fills space