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Grade 11 · Trigonometry
Trig Identities & Reduction Formulae: Full Guide
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/ 23
Answer all questions. Show all your working — marks are awarded for method as well as the final answer.
- 1Simplify sinθ · tanθ · cosθ, and state the restriction on θ. (simplify)(3)
- 2Simplify (1 − sin2θ). (identity)(1)
- 3Simplify cos2θ/(1 − sin2θ). (identity)(2)
- 4Prove tanθ · cosθ = sinθ, and say where the identity does not hold. (prove)(3)
- 5In which quadrant are only sine positive? (CAST)(1)
- 6sinθ = 0,5, θ in Q2. Is cosθ + or −? (CAST)(1)
- 7Simplify cos(180° − θ). (reduction)(1)
- 8Simplify sin(360° − θ). (reduction)(1)
- 9Exact value of sin 150°. (exact)(2)
- 10Exact value of cos 210°. (exact)(2)
- 11For which values of θ is tanθ undefined? Give the general answer.(2)
- 12For θ ∈ [0° ; 360°], state the values for which (sinθ × tanθ)/cosθ is undefined.(2)
- 13Explain why the restriction must be read off the ORIGINAL expression and not the simplified one.(2)
TOTAL: 23 marks