Comparison

InkDeck vs Arbitrary Triangle PRO

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

InkDeck

Create and study flashcards with handwritten notes and drawings. Supports spaced repetition, multiple study modes, and engaging games to make learning fun. Syncs across devices via iCloud without an account.

Highlights
  • Handwritten notes and drawings
  • Spaced repetition system
  • Multiple study modes (Quiz, Typing, Match)
  • Four built-in study games
  • Import Anki and CSV decks
  • Progress tracking and stats
  • iCloud sync across devices
Features
Read full description

InkDeck is the flashcard app you write by hand. Every card is a real drawing canvas — sketch diagrams, write formulas, practise kanji with Apple Pencil or your finger. One-time purchase. No subscription, no trial countdown, no AI upsell. BRING YOUR ANKI DECKS Import .apkg files properly — Ink reads the collection database and brings your images and audio across, not just the text. CSV import works too, and you can export to .inkdeck. STUDY FIVE WAYS • Standard Review — flip and self-rate, with spaced repetition that schedules each card at the right time, plus reminders • Quiz — four-choice questions with instant feedback • Typing — type your answer, with fuzzy matching so a typo isn't marked wrong • Match — tap to pair terms; Quick Fire, Batch Submit or Sliding Window • Cloze Deletion — fill in the blank from context FOUR GAMES BUILT IN Card Shooter, Balloon Pop, Pair Hunt and Word Forge turn review into something you'll actually open. RICH CARDS • Mix handwriting and typed text on the same card • Images, backgrounds and colour gradients • Record audio for pronunciation practice • Markdown for formatted text • Organise with groups, topics and tags TRACK YOUR PROGRESS A calendar heatmap, review history, correctness stats and retention curves show exactly how you're improving. Keep your streak alive. SYNCS, NO ACCOUNT Your decks sync over iCloud across iPhone and iPad. No sign-up, no account to create. Available in 11 languages: English, Spanish, French, German, Japanese, Korean, Portuguese, Russian, Turkish, Arabic and Chinese. Free to download with 3 sets of 10 cards. One purchase unlocks everything, forever, on every device on your Apple ID. https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

Arbitrary Triangle PRO

This app calculates all unknown quantities of an arbitrary triangle. It displays the formulas used and provides step-by-step solutions, supporting decimals and fractions. Calculations are saved in history and can be shared.

Highlights
  • Calculates all triangle quantities
  • Displays formulas used
  • Step-by-step solutions
  • Supports decimals and fractions
  • Calculation history
  • Shareable solutions
Features
Read full description

The best app to calculate all quantities of an arbitrary triangle. You must enter some quantities like two angles and one length. The algorithm searches the formulas of the missing quantities, shows them and calculates the results. The length of the decimal place can be changed. The algorithm shows when rounding or wrong values lead to an opposition. Decimals and fractions are supported. The solution is shown step by step. All calculations are stored in the history. The final solution can be shared. [ Contents ] - all important quantities for the arbitrary triangle - formulas for all important quantities of an arbitrary triangle - infographic to illustrate the topic - search bar to find the desired quantity - history function to save the input - detailed solution - positive numbers, decimals and fractions are supported - no ads! [ Usage ] - there are fields for entering values using a special keyboard - press the check mark button at the bottom right to start the calculation - if values are missing, all fields will be marked orange - if the values are wrong (e.g. negative lengths), the affected field will be highlighted red - if a value is no number, it is highlighted in red - the entries in the history can be deleted or sorted - if you select an entry in the history, it will be automatically loaded for the calculation - the whole history can be deleted by pressing a button - solutions can be shared [ Math conditions ] - each value must be greater than zero - each angle must be less than 180° - the sum of two sides must always be greater than the length of the third side

Screenshots

InkDeck4 screens
Arbitrary Triangle PRO4 screens

Verdict

The call

The clearest difference is price: InkDeck at Free against Arbitrary Triangle PRO's $2.99. InkDeck also leads on update cadence (every 9 days vs every 3 weeks). Arbitrary Triangle PRO's advantage is rating (5.0 vs 4.0) and in-app purchases (none vs 3). On ratings volume, ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

InkDeck is free to download; Arbitrary Triangle PRO costs $2.99 up front. InkDeck sells 3 in-app purchases, starting at $2.99 per month. Arbitrary Triangle PRO asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Arbitrary Triangle PRO holds the better App Store score, 5.0 against 4.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively.

UpkeepUpdate frequency

InkDeck ships an update every 9 days, Arbitrary Triangle PRO every 3 weeks. The most recent releases landed on September 18, 2026 and September 17, 2026 respectively.

Scorecard5 real differences · 4 level
InkDeck versus Arbitrary Triangle PRO: the parameters behind the verdict, then further details
ParameterInkDeckArbitrary Triangle PRO
PriceFree — better$2.99
Rating4.0 (1 ratings)5.0 (1 ratings) — better
Number of ratings11
Update frequencyEvery 9 days — betterEvery 3 weeks
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases — betterPaid
DevicesiPhone, iPad, MaciPhone, iPad, iPod
Requires iOS16.015.0 — better
Further details — not scored
Size18 MB182 MB
Age rating4+4+
DeveloperMuhammad MukhtarGlindemann, Sennoun, Langer GbR

Customer experience

InkDeck

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

Arbitrary Triangle PRO

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

3 purchases

InkDeck

Subscriptions2
  • App Access For 1 Month7 Days trial$2.991 Month
  • App Access For 1 Year7 Days trial$24.991 Year
One-time1
  • Unlimited cards$7.99
None

Arbitrary Triangle PRO

No in-app purchases

Questions

Is InkDeck free?
InkDeck is free to download, with in-app purchases available.
Is Arbitrary Triangle PRO free?
Arbitrary Triangle PRO costs $2.99, with no in-app purchases.
Which has better reviews, InkDeck or Arbitrary Triangle PRO?
Arbitrary Triangle PRO is rated higher. InkDeck averages 4.0 out of 5 from 1 ratings, while Arbitrary Triangle PRO averages 5.0 from 1 ratings.
Do InkDeck or Arbitrary Triangle PRO have ads?
Neither InkDeck nor Arbitrary Triangle PRO shows ads.
Which is updated more often, InkDeck or Arbitrary Triangle PRO?
InkDeck ships an update every 9 days, and Arbitrary Triangle PRO every 3 weeks. Most recently, InkDeck was updated on September 18, 2026 and Arbitrary Triangle PRO on September 17, 2026.

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