👉 Learn how to evaluate the cosine of an angle in radians using the sum/difference formulas. To do this, we first express the given angle as a sum or a difference of two (easy to evaluate) angles, ...

There are two versions of the cosine rule: Find an unknown side using 𝑎² = 𝑏² + 𝑐² – 2𝑏𝑐 cos𝐴 Find an unknown angle using cos𝐴 = \(\frac{𝑏² + 𝑐² – 𝑎²}{2𝑏𝑐}\) Scientific calculators need to ...

Using sine, cosine and tangent functions with right angled triangles. This resource gets students to recognise the hypotenuse, opposite and adjacent sides. This also get students practising using the ...

A large range of presentations and activities showing learners how to find missing lengths and angles of triangles by using the sine and cosine rule. Introduces radians and demonstrates how to convert ...