Ekuation

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Plate I.The gnomon and its shadowθ 35°h 12.0 mumbra s 17.14 mthe sunobeliskthe wellthe surveyorPl. I · h = 12.0 ms = 17.14 m · θ = 35°
35°
Shadow, s17.14 m
tan θ0.7002
Height, h = s × tan θ12.0 m

Fig. 1 — Sun at 35°: the shadow measures 17.14 m, so h = s × tan θ = 17.14 m × tan 35° = 12.0 m. Open the Triangle calculator →

The working, not just the answer.

Every calculator page shows the formula, plus a worked example with your inputs substituted. Each variable and assumption is documented. No black-box math.

Change a number ↘

Triangle · height from a shadowNoon on the terrace

m

°

Height, hs = 17.14 mhθ12.0 m

h = s × tan θ

  1. Substituteh = 17.14 m × tan 35°
  2. Tangenttan 35° = 0.7002
  3. Multiplyh = 17.14 × 0.7002 = 12.0 m
Open the full Triangle calculator →

Fig. 2 — The same triangle as the plate above. Change the shadow or the angle and the obelisk follows.

No. 01 · Noon

Every formula, shown.

The formula, then a worked example with your numbers in it. Each variable and assumption is documented.

Worked example

h = s × tan θ

h = 2.77 m × tan 77° = 12.0 m

Fig. 3 — Noon, sun at 77°: the shadow shrinks to 2.77 m. The obelisk is still 12.0 m.

No. 02 · Afternoon

It runs in your browser.

Calculations never reach a server. No accounts, no email list, no third-party trackers.

Network

NameStatusSize
—

0 requests · 0 B transferred

Fig. 4 — Afternoon in the harbour. Moving the sun recalculates in this page; the network panel stays empty.

No. 03 · Golden hour

Textbook math.

Built on math.js. Formulas come from textbooks and primary references, and each calculator documents its source and assumptions.

Source & assumptions

Formula
h = s · tan θ (right triangle)
Engine
math.js
Assumes
level ground, a vertical obelisk, shadow measured from its base
Fig. 5 — Golden hour, sun at 12°: the same 12.0 m obelisk throws a 56.46 m shadow. The formula does not change.

No. 04 · Dusk

Your inputs live in the link.

Copy the URL and opening it restores your inputs. Embed any calculator at /embed/[calculator-slug].

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ekuation.com/triangle-calculator?s=17.14&a=35Copy

Embed: /embed/triangle-calculator

Fig. 6 — Dusk. The link above carries this page's shadow and sun angle; it updates as you move the sun.

Frequently asked questions

Common questions about how Ekuation works, what it costs, and what to expect.

What is Ekuation?

A free online calculator catalog. Over 90 calculators across 19 categories — finance, science, health, math, conversions, everyday tasks. Every calculator shows the formula and a worked example. No account, no paywall, no ads.

How is Ekuation different from Omnicalculator?

Different priorities. Omnicalculator covers breadth (5,000+ tools). Ekuation focuses on showing the formula behind each calculator and explaining the math. Ekuation also runs no ads, requires no signup, and supports German.

Is Ekuation free?

Yes. No account, no payment, no ads, no premium tier, no upsell. Every calculator works without restriction. Use any of them as much as you want.

Do I need an account to use Ekuation?

No. Click any calculator, enter your inputs, get the result. No signup, login, or email field. Bookmark a calculator and come back whenever — the URL works without authentication.

What categories of calculators are there?

19 categories: math, finance, science, health, food, music, sports, time, and everyday-life tasks. Each category groups calculators with their formulas and step-by-step worked examples. Browse them on the homepage.

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Fig. 8 — Night. No sun, no shadow, no triangle. The lighthouse keeps the harbour until morning.

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