Eric Nicholas K's answer to trish's Secondary 4 A Maths Singapore question.
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You need to know three things here.
1. Logarithmic rules. You can’t split the ln here sadly due to the rules.
2. Differentiation rule via chain rule.
3. Trigo identities.
Also note that sec x is the same as 1 / cos x or (cos x)^-1, but these are not the same as cos^-1 x since cos^-1 x is reserved for the inverse of cosine (cos^-1 x = k means the angle for which cos k = x). For all other powers, cos^n x = (cos x)^n.
1. Logarithmic rules. You can’t split the ln here sadly due to the rules.
2. Differentiation rule via chain rule.
3. Trigo identities.
Also note that sec x is the same as 1 / cos x or (cos x)^-1, but these are not the same as cos^-1 x since cos^-1 x is reserved for the inverse of cosine (cos^-1 x = k means the angle for which cos k = x). For all other powers, cos^n x = (cos x)^n.
Date Posted:
4 years ago
thank you so much! :)
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