GCSE Secondary Maths Age 13-17 - Pythagoras & Trigonometry: Cosine Rule - Explained

The video tutorial explains how to solve a triangle problem without a right angle using the sine and cosine rules. It begins by identifying the given data, including the triangle's area and an angle. The instructor demonstrates how to use the area formula to find the length of side BC, emphasizing the importance of maintaining accuracy by not rounding off early. The cosine rule is then applied to find the unknown side, with detailed steps on using a calculator correctly. The tutorial concludes with a discussion on rounding the final answer to three significant figures and the allocation of marks for each step.

Why is it important to show all working in mathematical problems?

Describe the process of using the cosine rule to find the length of a side in a triangle.

What is the final answer for the length of side AB after rounding to three significant figures?