If α ∈ (0, π) and cos α + sin α = - 1 / 3, then Cos2 α=

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• 1. Sin α + sin β = 1. Cos α + cos β = 0 find Cos2 α + Cos2 β
• 2. If α ∈ (0, π), sin α + cos α = 1 / 3, find Tan α, Cos2 α, etc!
• 3. If α belongs to (0, π) and cos α + sin α = - 1 / 3, then Cos2 α =?
• 4. If θ is the second quadrant angle and cos θ / 2-sin θ / 2 = √ (1-2 sin θ cos θ), then what quadrant angle is θ / 2
• 5. It is known that a is the third quadrant angle, and COS (A / 2) + sin (A / 2) = - (√ 6) / 3, √ (1 + COSA) = - {2Sin (A / 2) 1 ask me to calculate the value of COS (A / 2) - sin (A / 2) 2 question: （cos(a/2)*cos(a+3.14/4))/(1+tan(a/2))
• 6. The result of 2 + cos2-sin1 ^ 2 under the root sign is A cos1 B sin1 C √3 *cos1 D -√3*cos1
• 7. Cos2 β = - (1 / 2), then sin β=
• 8. If a belongs to {0, π / 2} and COS square a + sin {π / 2 + 2A} = 1 / 2, then Tana =?
• 9. Simplification: 1, sin (x - π / 3) - cos (x + π / 6) + √ 3cosx =? 2, known, sin α + sin β = √ 2 / 2, find the value range of cos α + cos β
• 10. Y = cos square x-sin square x + 3sinx Find the maximum and minimum
• 11. If α∈ (0, π) and cos α + sin α = - 13, then Cos2 α = () A. 179B. ±179C. −179D. 173
• 12. sinα=1/3 cos2α=
• 13. Given sin θ ...
• 14. Cos (x / 4 - α) = 12 / 13, α ∈ (0, π / 4), find (Cos2 α) / [sin (π / 4 + α)] Cos (x / 4 - α) = 12 / 13, α ∈ (0, π / 4), find (Cos2 α) / [sin (π / 4 + α)]
• 15. Cos 2 α = - 3 / 5, α ∈ (π / 2, π), sin β = - 12 / 13, the third quadrant of β, find cos (β - α) Delete Cos2 α = - 3 / 5 and change to cos α = - 3 / 5
• 16. If sin β = - 5 / 13, α∈ (π / 2, π), then Cos2 α=
• 17. Given sin α = 3 / 5, what is the value of Cos2 α?
• 18. If Cos2 α = a, find the value of Sin & # 8308; α - cos & # 8308; α
• 19. Given sin θ 2 + cos θ 2 = 233, then the value of sin θ is______ The value of Cos2 θ is______ ．
• 20. It is known that a quarter of the faction is less than a half of the faction, and sin AFA + cos AFA = seven fifths, so cos AFA sin AFA can be obtained