Use of double angle formulae It's good to know that to solve any trigonometric equation involving sin 2 x and either sin x or cos x, the process is the same.

Angle Formulas in Trigonometry: Definition, Representaion, Questions & More Check definition and formulas for central angle, double angle and multiple angles.

This uses the trigonometry sum of angles formula and breaks the cosine into a function of sines and cosine with angles that we know the answer for (45° and 30°).

Revise trigonometric ratios of sine, cosine and tangent and calculate angles in right-angled triangles with this Bitesize GCSE Maths Edexcel guide.