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secondary 3 | A Maths
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Shalyn
Shalyn

secondary 3 chevron_right A Maths chevron_right Singapore

Help with tan3A

Date Posted: 3 years ago
Views: 280
J
J
3 years ago
tan 2A

= 2tanA / (1 - tan² A)

= 2(½) / (1 - (½)²)

= 1 / (1 - ¼)

= 1 / ¾

= 4/3
J
J
3 years ago
tan 3A

= tan (A + 2A)

= (tan A + tan 2A) / (1 - tan A tan 2A)

= (½ + 4/3) / (1 - ½(4/3) )

= (11/6) / (⅓)

= 11/6 x 3/1

= 11/2

= 5½
Shalyn
Shalyn
3 years ago
How u get 4/3 for the tan3A
J
J
3 years ago
You mean tan 2A. It has already been found to be 4/3 in the first part. So simply substitute it into the second part when you're solving for tan 3A
Shalyn
Shalyn
3 years ago
Right thanks!

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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
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A rough idea
J
J
3 years ago
Will be better to leave final answer as mixed number 5½