Trigonometry Foundations
Which side is opposite, which is adjacent, and which is the hypotenuse — and then the three ratios, written as exact fractions. No calculator, no tables, no rounding.
No account, and the maths stays in your browser — more— less
This activity is for learning and practice. Anything it suggests is indicative only — it is not a formal assessment and not a substitute for a teacher or tutor.
Nothing you answer is sent to Zerdly. Progress is saved on this device only if you switch saving on, and you can delete it at any time. How Kids Maths handles data.
Set your country and age — change
Setting an age keeps the questions at the right level for that age. It does not lock anything — you can still try any topic, at any age, in any order. Levels are a guide only, not a curriculum.
Your age is not saved anywhere. Your country is remembered only if you have switched saving on.
Saving your progress
Nothing is being saved. You can practise as much as you like — when you close the tab, the session is gone.
Opposite and adjacent are not fixed names
They describe a relationship to the angle you are looking at. Stand at the other corner and the same two sides swap names. That is why the first four levels do nothing but naming, from both angles in the same triangle — it is most of the difficulty, and everything after it is a fraction.
The hypotenuse is the one that never changes
It is opposite the right angle, whichever corner you stand at, and it is always the longest side. Find it first and the other two sort themselves out.
Why there is no calculator here
Every triangle in this tool has whole-number sides, so sine, cosine and tangent all come out as exact fractions like 3/5 or 12/13. That means what is the tangent of this angle has a written answer you can check — which is practice, rather than typing numbers into a machine and copying out what comes back.
School levels
School levels are a guide only. They show where a skill is usually taught in each country and are not taken from, aligned to, or endorsed by any curriculum authority. Your school may cover it earlier or later.