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Trigonometry - Compound and Double-Angle Identities

Trigonometry - Compound and Double-Angle Identities

TGM Original Questions

Given that \(ABC\) is a triangle and \(\tan \frac{A}{2} = \frac{1}{4}\), without using a calculator, find

  1. \(\tan A\)
  1. \(\sin (B + C)\)
  1. \(\cos A\)
  1. \(\cos (B + C)\)

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Answer:(i) \(\dfrac{8}{15}\); (ii) \(\dfrac{15}{17}\); (iii) \(\dfrac{8}{17}\); (iv) \(-\dfrac{15}{17}\)

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