求詳細步驟！
17. cos43°=sin(75°-Θ)
答案：28°
18. sin32°=cos(66°-Θ/2)
答案：16°
19. tan(Θ+15°)=1/tan(Θ+60°)
答案：7.5°
20. tan(Θ+45°)=1/tanΘ/4
答案：36°
三角恆等式問題！
2011-02-20 7:12 pm
回答 (1)
2011-02-20 7:22 pm
✔ 最佳答案
17)cos43° = sin(75°-Θ)sin(90 - 43) = sin(75 - Θ)90 - 43 = 75 - ΘΘ = 28°18)sin32° = cos(66° - Θ/2)cos(90 - 32) = cos(66° - Θ/2)90 - 32 = 66 - Θ/2Θ/2 = 8Θ = 16°
19)tan(Θ+15°) = 1 / tan(Θ+60°)tan(Θ+15) = tan(90 - (Θ+60))Θ+15 = 90 - (Θ+60)2Θ = 15Θ = 7.5°
20)tan(Θ+45°) = 1 / tan(Θ/4)tan(Θ+45°) = = tan(90 - Θ/4)Θ+45° = 90 - Θ/44Θ + 180 = 360 - Θ5Θ = 180Θ = 36°
收錄日期: 2021-04-21 22:22:16
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110220000051KK00393