ABSTRACT
To ‘solve a triangle’ means ‘to find the values of unknown sides and angles’. If a triangle is right-angled, trigonometric ratios and the theorem of Pythagoras may be used for its solution, as shown in Chapter 22. However, for a non-right-angled triangle, trigonometric ratios and Pythagoras’ theorem cannot be used. Instead, two rules, called the sine rule and cosine rule, are used.
