1.3cos20+1=1.5
2.2cos30-3=-2
3.2sin0=sin40度
4.3cos0=2sin20度
所有0係sine符號既0中間加一橫線既0,需列式!
有關sine既問題
2006-11-11 4:14 am
回答 (2)
2006-11-11 4:26 am
✔ 最佳答案
1.3cos2θ+1=1.53cos2θ=0.5
cos2θ=1/6
θ=40.2∘
2.2cos3θ-3=-2
2cos3θ=1
cos3θ=1/2
3θ=60∘
θ=20∘
3.2sinθ=sin40∘
θ=18.7∘
4.3cosθ=2sin20∘
θ=76.8∘
參考: answer are in 3 s.f. some are calculated by calculator
2006-11-11 7:02 pm
1.
3cos2θ + 1 = 1.5
3cos2θ = 1.5 – 1
cos2θ = 0.5/3
cos2θ = 1/6
2θ = cos-1 (1/6)
θ = [cos-1 (1/6)] /2
θ = 40.2° (準確至三位有效數字)
2.
2cos3θ – 3 = - 2
2cos3θ = - 2 + 3
cos3θ = 1/2
3θ = cos-1 (1/2)
3θ = 60°
θ = 60°/3
θ = 20°
3.
2sinθ = sin40°
sinθ = (sin40°) /2
θ = sin-1 [(sin40°) /2]
θ = 18.7° (準確至三位有效數字)
4.
3cosθ = 2sin20°
cosθ = (2sin20°) / 3
θ = cos-1 [(2sin20°) / 3]
θ = 76.8° (準確至三位有效數字)
P.S.
cos-1 = shift cos (計數機)
sin-1 = shift sin (計數機)
3cos2θ + 1 = 1.5
3cos2θ = 1.5 – 1
cos2θ = 0.5/3
cos2θ = 1/6
2θ = cos-1 (1/6)
θ = [cos-1 (1/6)] /2
θ = 40.2° (準確至三位有效數字)
2.
2cos3θ – 3 = - 2
2cos3θ = - 2 + 3
cos3θ = 1/2
3θ = cos-1 (1/2)
3θ = 60°
θ = 60°/3
θ = 20°
3.
2sinθ = sin40°
sinθ = (sin40°) /2
θ = sin-1 [(sin40°) /2]
θ = 18.7° (準確至三位有效數字)
4.
3cosθ = 2sin20°
cosθ = (2sin20°) / 3
θ = cos-1 [(2sin20°) / 3]
θ = 76.8° (準確至三位有效數字)
P.S.
cos-1 = shift cos (計數機)
sin-1 = shift sin (計數機)
收錄日期: 2021-04-12 22:58:25
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20061110000051KK03501