prove that: tan (2 x 30°) = 2 tan 30 ° 1 – tan 2 30 ° - Mathematics

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Sum

prove that:

tan (2 x 30°) = `(2 tan 30°)/(1– tan^2 30°)`

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Solution

RHS,

`(2 tan^2 30°)/(1 – tan^2 30°) = (2 (1)/sqrt3)/(1– 1/3) = (2/sqrt3)/(2/3) = sqrt3`

LHS,
tan (2 x 30°) = tan 60° = `sqrt3`
LHS = RHS

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Chapter 23: Trigonometrical Ratios of Standard Angles [Including Evaluation of an Expression Involving Trigonometric Ratios] - Exercise 23 (A) [Page 291]

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Selina Concise Mathematics Class 9 ICSE
Chapter 23 Trigonometrical Ratios of Standard Angles [Including Evaluation of an Expression Involving Trigonometric Ratios]
Exercise 23 (A) | Q 4.3 | Page 291
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