How to Learn Trigonometry (SOH CAH TOA)
Trigonometry links the angles of a right triangle to the lengths of its sides, through three ratios — sine, cosine and tangent. One mnemonic, SOH CAH TOA, unlocks all of it. This deck teaches the ratios, the mnemonic and the key angle values.
There are 12 cards in the deck below. You can read through them, practise them right here with the flip-card player, and then save the deck to study properly with spaced repetition — the method that makes them stick for months, not minutes.
Why the basics of trigonometry is hard to memorize (and the fix)
Beginners forget which ratio uses which sides (does tangent use the hypotenuse?). SOH CAH TOA spells it out, and learning the exact values for 0°, 30°, 45°, 60° and 90° covers most exam questions.
The fix is active recall plus spaced repetition. Instead of re-reading the list (which feels productive but barely works), you test yourself — pull each answer out of memory — and you review each card on a schedule that stretches over time. Every time you successfully recall a fact, the memory gets stronger and the next review is pushed further out. That's how you go from "I saw it once" to "I just know it."
The fastest way to learn the basics of trigonometry
- Break it into small batches. Learn the three ratios with SOH CAH TOA first, then the exact values of the common angles.
- Test, don't re-read. Look at the question, say the answer out loud before flipping the card. The little struggle to recall is what builds the memory — a smooth re-read does almost nothing.
- Review on a schedule. Spaced repetition shows you each card right before you'd forget it. Get one right and it comes back in a few days, then a week, then a month. Miss one and it comes back sooner.
- Keep sessions short and daily. Five to ten minutes a day beats a two-hour cram every time. Consistency is the whole game.
One fact per card. The hypotenuse is always the longest side (opposite the right angle); "opposite" and "adjacent" are relative to the angle you are using.
The full deck: Trigonometry (SOH CAH TOA)
Here's every card in the set. Practise them above, or save the deck and let spaced repetition schedule your reviews automatically.
| Question | Answer |
|---|---|
| What does SOH CAH TOA stand for? | Sine = Opp/Hyp, Cosine = Adj/Hyp, Tangent = Opp/Adj |
| What is sine of an angle? | Opposite ÷ hypotenuse |
| What is cosine of an angle? | Adjacent ÷ hypotenuse |
| What is tangent of an angle? | Opposite ÷ adjacent |
| Which side is the hypotenuse? | The longest side, opposite the right angle |
| What is sin(0°)? | 0 |
| What is sin(30°)? | 0.5 (½) |
| What is sin(90°)? | 1 |
| What is cos(0°)? | 1 |
| What is cos(60°)? | 0.5 (½) |
| What is tan(45°)? | 1 |
| What is the Pythagorean theorem? | a² + b² = c² (for a right triangle) |
Save this deck and actually remember it
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Study this deck free →FAQ: learning the basics of trigonometry
How long does it take to learn the basics of trigonometry?
Most people can lock in the basics of trigonometry within one to three weeks of short daily sessions. With spaced repetition doing 10–12 cards a day, you'll recognise them within days and recall them reliably within a couple of weeks.
What's the best way to memorize the basics of trigonometry?
Active recall plus spaced repetition. Test yourself instead of re-reading, and review on a schedule that spaces the cards out over time. Flashcards are built for exactly this — which is why the deck above is the fastest path.
Is this deck free?
Yes. You can practise all 12 cards on this page for free with no account. Sign up (also free) to save the deck and let spaced repetition schedule your reviews so it sticks long-term.