Trigonify: Trig You Can Actually See

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App Screenshot
App Screenshot
App Screenshot
App Screenshot
App Screenshot
App Screenshot
App Screenshot

I built Trigonify because most trig apps just hand you an answer. That helps with tonight's homework but not with the test.

The part I'm most proud of is the unit circle. You drag the angle with your finger and the sine wave next to it moves at the same time. Textbooks try to show this with a still picture and it never really lands. When you can move it yourself, it does.

The rest is the toolkit you'd expect, done properly. The triangle solvers handle right and oblique triangles and show every step, including the SSA case where two different triangles are both valid. There's a grapher where you drag amplitude, period and phase. There's an identity checker that uses a real algebra engine, so it actually proves the identity and also checks it with numbers. And there's a formula sheet plus practice that keeps track of which skills you're weak on.

Two things I cared about while building it. First, it works with no internet. The math rendering is bundled inside the app, so it works on the bus or in a classroom with bad wifi. Second, all the graphics are drawn live with Skia. Nothing is a static image, which is why you can touch everything.

It's free for right triangles, inverse trig, the unit circle and practice. Pro adds oblique triangles, the grapher, complex numbers, vectors, the identity checker and PDF export. Purchases run through RevenueCat with weekly, yearly and lifetime options.