Cambridge O Level Mathematics (Syllabus D) · Syllabus 4024 · Trigonometry
Non-Right-Angled Triangles
What is Non-Right-Angled Triangles?
Triangles containing no right angle, solved with three formulas supplied on the examination paper. The sine rule, a over sine A equals b over sine B, applies when a side is known together with the angle opposite it. The cosine rule, c squared equals a squared plus b squared minus 2ab cos C, applies to two sides with their included angle, and rearranges to give an angle when all three sides are known. The area is half ab sin C, where C is the angle enclosed between sides a and b. Conventional labelling places side a opposite angle A, and where two sides and a non-included angle are given the sine rule produces two candidate angles that must both be tested.
This definition is part of the Trigonometry chapter in Cambridge O Level Mathematics (Syllabus D).