In triangle, tanA+tanB+tanC=tanA*tanB*tanC

In triangle, tanA+tanB+tanC=tanA*tanB*tanC
arctan1+arctan2+arctan3=pi

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Probability and discrete mathematics:

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Probability interview questions:

https://www.youtube.com/watch?v=qphhG_1rWf8&list=PLg9w7tItBlZtI1eM6znSYfyDEaqQtUx5b

Probability theory:

https://www.youtube.com/watch?v=8s-nyRLBsDo&list=PLg9w7tItBlZsvciKHBx8lXXnCtQ7Ou4cV

Complex analysis:

https://www.youtube.com/playlist?list=PLg9w7tItBlZsYfYG6dUISItqsSRSXaX4B

Combinatorics:

https://www.youtube.com/playlist?list=PLg9w7tItBlZvQt0YNfCqcULzrPme2ai7K

additive combinatorics:

https://www.youtube.com/playlist?list=PLg9w7tItBlZseUrmXgf_2yc2NI_obVUhB

微積分 高等微積分 代數

Calculus and advanced mathematics (abstract algebra):

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Real analysis

https://www.youtube.com/playlist?list=PLg9w7tItBlZumEJ4DacAKgstCvDHKtY63

Reduction formula in Calculus:

https://www.youtube.com/playlist?list=PLg9w7tItBlZubmhgkHoHvje1uOASnkcke

Integrals of trigonometric functions:

https://www.youtube.com/playlist?list=PLg9w7tItBlZuwEER2YvFV06ri6i1Cj3hh

(algebraic geometry)代數幾何筆記

https://www.youtube.com/playlist?list=PLg9w7tItBlZssQ4Smzgp_bk2rEszKaW0B

Linear algebra Proof:

https://www.youtube.com/playlist?list=PLg9w7tItBlZueH6LMeYzzwPMUlIaRhCZo

環論(ring theory):

https://www.youtube.com/playlist?list=PLg9w7tItBlZs9w4wrNAuv4oJdrt-sIWUP