Solve the triangle below approximating the lengths to the nearest centimetre and the measures of angles to the nearest second.
Since we have been given the lengths of two sides of the triangle and the measure of the included angle, we can apply the cosine rule to calculate the length of the missing side.
For triangle , we have
Therefore, we can apply the cosine rule to calculate .
Now we can apply the cosine rule again to calculate .
Since the sum of the measures of the angles in a triangle is , we can calculate the measure of the final angle in the triangle as follows: