One Question, One Answer

You'll learnto see why each inverse trig function returns exactly one angle.

“Which angle has sine one half?” has infinitely many correct answers, and a function is allowed to return exactly one. So each inverse trig function comes with a contract: a restricted range it promises never to leave. Watch the restriction get carved out, then watch the graph fold across y = x.

8 STEPS · 6 QUICK CHECKS · RESTRICTION · REFLECTION · RANGE CONTRACTS · v2

one question, one answer

Before you start

What you're looking at

sin θ = 1/2 with several correct angles counted around the circle.

The question

A function may return only one output — which of the many correct angles should it give?

Watch for

The restricted range carved out and highlighted before the graph folds across y = x.

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