The equation 2sec2x+4tan2x=−5secx2 \sec^2 x + 4 \tan^2 x = -5 \sec x2sec2x+4tan2x=−5secx can be written in the form 6sec2x+5secx−4=06 \sec^2 x + 5 \sec x - 4 = 06sec2x+5secx−4=0.
Hence, given x x\,x is obtuse find the exact value of tanx\tan xtanx.
274 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.