The trigonometric ratios sine, cosine and tangent are used to calculate angles and sides in right angled triangles. We are now going to extend trigonometry beyond right angled triangles and use it ...

It may be necessary to use Pythagoras' theorem and trigonometry to solve a problem ... button on the calculator \(x = 25.4^\circ\). The cosine rule is: \(a^2 = b^2 + c^2 - 2bc \cos{A}\).