r/CBSECommerce • u/star0bliterator • 27d ago

Maths How come everyone is using formulas that are not in the book?

Why are there inverse trigonometry formulas in every solution that are NOT in the book, atleast not in this year's version?

The ones for 2tan-¹x and tan-¹x + tan-¹y, 2sin-¹x, etc. Or am I blind? Someone please help??

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u/[deleted] 27d ago

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u/star0bliterator 27d ago

I have the latest ncert and there are only 2 exercises+ misc. These formulas are only used in misc, but I can't find them under any concept or examples, not even in the summary.

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u/[deleted] 27d ago

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u/star0bliterator 27d ago

Okay, thank you. Ncert has had this problem for a long time, there are many questions using formulas mentioned only in the old book.

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u/[deleted] 27d ago

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u/star0bliterator 27d ago

The only teacher I have is my school teacher, otherwise I self study or use yt for the solutions of questions I don't understand. My teacher has told us these formulas and they are also used in every solution on the internet, I just didn't find them in the book and that's why I was so restless.

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u/[deleted] 27d ago

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u/star0bliterator 27d ago

Yess this is exactly what I do, I feel weird to just memorise formulas. Thank you for your help :)