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 ...

Revise using the sine and cosine rules to find a side or angle in a triangle for National 5 Maths. National 5 Maths - Using the sine and cosine rules to find a side or angle in a triangle.