In triangle DEFDEFDEF, ED=5cmED = 5\text{cm}ED=5cm and EF=6cmEF = 6\text{cm}EF=6cm. Given that sin(∠DEF)=23\displaystyle \sin(\angle DEF) = \frac{2}{3}sin(∠DEF)=32 and ∠DEF \angle DEF\,∠DEF is acute.
Find the exact value of cos(∠DEF)\cos(\angle DEF)cos(∠DEF)
Find the length of DFDFDF.
Find ∠EFD\angle EFD∠EFD.
Practise Edexcel AS Level Maths Trigonometric Ratios with exam-style questions for AS Level Maths. 20 questions 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, matched to the Edexcel AS Level Maths (8MA0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.