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junior college 1 | H2 Maths
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Dave
Dave

junior college 1 chevron_right H2 Maths chevron_right Singapore

Can't get the answer by letting sin x =x , tan x=x and cos x = 1- x^2/2. Please help. Thank you.

Date Posted: 1 year ago
Views: 368

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Boy Mow Chau
Boy Mow Chau's answer
316 answers (Tutor Details)
1st
x is small, but (π/4+x) is not small !
have to use compound angle formula to expand
sin(pi/4 + x) first ...

similarly, x is small, but 2x may not be small ...
use double angle formula for tan2x.

thereafter, expand & simplify, ignoring any powers of x3 & higher.
Dave
Dave
1 year ago
Thank you