Ng Ye kai's answer to Priya's Secondary 4 A Maths Singapore question.
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Just apply the addition trigo formula
Date Posted:
3 years ago
① the formula used is actually the reverse of the factor formula (or sum to product formula) and not the addition formula.
Besides, this formula is not covered in O level A Math nowadays.
② integration of cos gives sin and not -sin.
Besides, this formula is not covered in O level A Math nowadays.
② integration of cos gives sin and not -sin.
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