急! F4 Basic Trigonometry 13q2

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2012-05-02 3:46 pm

請詳細步驟教我計以下幾條 :(不要網址回答) Solve the following equations
19. sinθ- cosθ= 0, where 0 < θ < 27020. 3cosθ+ 4sinθ= 0, where 0 < θ < 36021. tanθ(3sinθ+2) = 0, where 0 <= θ < 36022. 4cosθsinθ+cosθ = 0, where 0 <= θ < 36023. sinθ- √3 tanθ = 0, where 0 <= θ < 36024. √2sinθ = tanθ, where 0 <= θ < 360

回答 (1)

用戶25975

2012-05-02 5:13 pm

✔ 最佳答案

19) sin θ - cos θ = 0

sin θ = cos θ

tan θ = 1

θ = 45 or 225

20) 3 cos θ + 4 sin θ = 0

4 sin θ = - 3 cos θ

tan θ = -3/4

θ = 143.4 or 323.4

21) tan θ (3 sin θ + 2) = 0

sin θ (3 sin θ + 2) = 0 provided that cos θ =/= 0

sin θ = 0 or -2/3

θ = 0 or 180 or or 221.8 or 318.2

22) 4 cos θ sin θ + cos θ = 0

cos θ (4 sin θ + 1) = 0

cos θ = 0 or sin θ = -1/4

θ = 90 or 270 or 194..5 or 345.5

23) sin θ - √3 tan θ = 0

sin θ (1 - √3/cos θ) = 0

sin θ = 0 or cos θ = √3 (rejected)

θ = 0 or 180

24) √2 sin θ = tan θ

√2 sin θ = sin θ/cos θ

√2 sin θ - sin θ/cos θ = 0

sin θ (√2 - 1/cos θ) = 0

sin θ = 0 or cos θ = 1/√2

θ = 0 or 180 or 45 or 315

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