# Rational Sine and Cosine

Pro Problems > Math > Logic > Proofs## Rational Sine and Cosine

There are infinitely many angles θ between 0º and 90º for which both sin θ and cos θ are rational numbers. Prove this statement.

Hint: Here are some examples:

sin θ

cos θ

3

5

4

5

5

13

12

13

7

25

24

25

9

41

40

41

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Problem by Mr. Twitchell

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