Trigonometric Ratios of Acute and Obtuse Angles

Trigonometric Ratios of Acute and Obtuse Angles

Secondary 3

Find obtuse angles \(A\) and \(B\) such that

\(\cos A=-0.785\)
\(\sin B=0.866\)

giving your answers correct to \(1\) decimal place.

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Answer:(i) \(A=141.7^\circ\) (ii) \(B=120.0^\circ\)

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