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secondary 4 | A Maths
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Hi! can someone please help me w this question? Thank u !!!!!! :-))))
I give you a small clue first, 15 = 45 - 30 while 75 = 45 + 30.
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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!