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secondary 4 | A Maths
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How do they get the value in the indicated bracket? Isn't it supposed to be (7π/12 + π/12) in the indicated bracket and not (7π/12 - π/12)? Please help to explain
Date Posted: 5 years ago
Views: 339
The answer key is correct. Your might want to check out product-sum identities.
https://www2.clarku.edu/faculty/djoyce/trig/identities.html
https://www2.clarku.edu/faculty/djoyce/trig/identities.html
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These are the trigo formula that you’re expected to know for Amaths! So you just have to sub in and use the formula, there isnt an explanation for it, unless you google and read the explanation. Hope it helps!
Date Posted:
5 years ago
Never come across these formulas before.Apparently,the formulas were not introduced to amath students studying in the current syllabus.Using it may not mean anything yet unless the syllabus changes again..Didn't learn to apply them..Otherwise,I may have mislook it..Whatever it is thanks for sharing something new..Appreciate it. :)
Thank you so much
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This is another way of getting the answer..I'm afraid i can't explain how the expression can be changed into a double angle form..But I do have a reason for my own working of why the values are the same bur not the sign or placing.Basically,you have to make use of the special angles you know that is equal to the angel inside each trigo function (Sin).Its easier to expand sin(45+60) rather than looking at sin(105) alone..You can't do anything about it but the former helps in expanding using r-formulae..Isn't 45+60=105?.Thats why you have 45+60 & 60-45 where the values are the same..You have learnt the values of special angels so it's easier to do the qn..Hope it helps :)
Date Posted:
5 years ago
Don't mind the typo error..
Thank you so much:)
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