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Which side ratio gives sinx\sin xsinx in a right-angled triangle?
A
The tangent identity is tanx≡sinxcosx\boxed{\tan x\equiv\dfrac{\sin x}{\cos x}}tanx≡cosxsinx, where cosx≠0\cos x\neq0cosx=0.
B
Every side gains the same scale factor, which cancels in each ratio.
C
Taking a square root when finding cosine gives cosx=±1−sin2x\boxed{\cos x=\pm\sqrt{1-\sin^2x}}cosx=±1−sin2x; the quadrant determines the sign.
D
oppositehypotenuse\dfrac{\text{opposite}}{\text{hypotenuse}}hypotenuseopposite
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1.4.5 Trigonometry Flashcards
20 flashcards on CCEA A Level Maths 1.4.5 Trigonometry: the key formulae, methods and definitions you need to recall for AS 1, AS 2, A2 1 and A2 2.