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secondary 4 | A Maths
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Sonia
Sonia

secondary 4 chevron_right A Maths chevron_right Singapore

Hi! can someone please help me w this question? Thank u !!!!!! :-))))

Date Posted: 4 years ago
Views: 294
Eric Nicholas K
Eric Nicholas K
4 years ago
Good evening Sonia! I will do these for you later before 3 am.

I give you a small clue first, 15 = 45 - 30 while 75 = 45 + 30.

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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
1st
Good evening Sonia! Here are my workings for this question.

Parts a and b are very similar, where we express 15 and 75 as 45 - 30 and 45 + 30 and then use the addition angle formula to simplify the expression. We need to know the special angle values as well.

Part c is quadratic factorisation a2 - b2 = (a + b) (a - b).

Part d uses the complementary angle rule, cos x = sin (90 - x).

Part e is simplification from parts c and d.

Let me know if you need more explanation and I will do my best to explain them again!
Sonia
Sonia
4 years ago
Thank u Eric for always providing me with quick and good solutions!!! :-) truly appreciate it