Show that the equation 2sec2x+4tan2x=5secx2 \sec^2 x + 4 \tan^2 x = 5 \sec x2sec2x+4tan2x=5secx can be written in the form asec2x+bsecx+c=0a \sec^2 x + b \sec x + c = 0asec2x+bsecx+c=0
Hence, given x x\,x is obtuse find the exact value of tanx\tan xtanx.
54 exam-style questions on Edexcel A Level Maths Trigonometric Functions, covering 6.1 Secant, Cosecant and Cotangent, 6.2 Graphs of Sec x, Cosec x and Cot x, 6.3 Using Sec x, Cosec x and Cot x, 6.4 Trigonometric Identities, and 6.5 Inverse Trigonometric Functions. Each one has a worked solution and a mark scheme showing where the marks go.