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secondary 3 | A Maths
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secondary 3 chevron_right A Maths chevron_right Singapore

do help with (b) thanks

Date Posted: 3 years ago
Views: 271
Justin
Justin
3 years ago
==> sin(5x)/cos(5x) = sin(2x)/cos(2x)

Cross multiplying, ==> sin(5x)cos(2x) = cos(3\5x)sin(2x)

==> sin(5x)cos(2x) - cos(5x)sin(2x) = 0

==>sin(5x - 2x) = 0 [Applying sin(A - B) = sinAcosB - cosAsinB]

==> sin(3x) = 0

==> sin(3x) = sin(nπ), where 'n' is an integer.

==> 3x = nπ

Thus 'x = nπ/3 radians'
Justin
Justin
3 years ago
means x = n times 60 degree, where n = 1,2,3 etc--> in this case n can be 1 to 5

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Mr Ang
Mr Ang's answer
347 answers (A Helpful Person)
1st
Kindly verify the workings eh, thanks.
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3 years ago
thank you
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3 years ago
thank you
Mr Ang
Mr Ang
3 years ago
You're welcome.