In triangle ABCABCABC, side AB AB\,AB has length 5 cm, side BC BC\,BC has length 9 cm and side AC AC\,AC has length 7 cm.
Show that the cosine of angle ACB ACB\,ACB is 56\displaystyle \frac{5}{6}65.
Show that the exact area of the triangle is 21114 cm2\displaystyle \frac{21\sqrt{11}}{4}\text{ cm}^242111 cm2.
217 exam-style questions on Edexcel A Level Maths Trigonometric Ratios, covering 9.1 The Cosine Rule, 9.2 The Sine Rule, 9.3 Areas of Triangles, 9.4 Solving Triangle Problems, 9.5 Graphs of Sine, Cosine and Tangent, and 9.6 Transforming Trigonometric Graphs. Each one has a worked solution and a mark scheme showing where the marks go.