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Trigonometry - Cosine Rule

Trigonometry - Cosine Rule

IP 2

In the diagram, \(AB = 4\) cm, \(BC = 7.5\) cm, \(AD = 5\) cm, \(BD = 6.2\) cm and \(\angle BDC = 55^\circ\).

Calculate

  1. \(\angle ADB\),
  2. \(\angle BCD\),
  3. the area of \(ABCD\).

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Answer:(i) \(40.1^\circ\) (ii) \(42.6^\circ\) (iii) \(33.0\text{ cm}^2\)

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