# Pythagorean identities

Source: https://projectalevel.co.uk/maths/trigonometry/pythagorean_identities

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- This important identity can be derived as a direct result of Pythagoras's theorem, when applied to angles in trigonometry:
- sin²x + cos²x = 1 (1)
- By dividing each of these terms by sin²x, we can derive a second identity:
- 1 + cot²x = cosec²x
- By dividing (1) by cos²x, we arrive at the third (and final) identity:
- tan²x + 1 = sec²x