急! Basic Trigonometry 13Q1

2012-06-20 9:18 am
如果 tan x=tan 130
=tan(180-50)
x=180-50 or 360-50
答案是=130 or 310

咁以下幾條又點計 ? 請詳細步驟,不要網址回答.
1. sin x = sin 313
2. sin x = -sin 316
3. cos x = -cos 203
4. cos x = cos 181
5. tan x = tan 316
6. tan x = -tan 27

回答 (1)

2012-06-20 11:36 am
✔ 最佳答案
Assume that 0° ≤ x ≤ 360°

1.
sin x = sin 313°
sin x = sin (360° - 47°)
sin x = -sin 47°
x = (180° + 47°) or x = (360° - 47°)
x = 227° or x = 313°


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2.
sin x = -sin 316°
sin x = -sin (360° - 44°)
sin x = -(-sin 44°)
sin x = sin 44°
x = 44° or x = (180° - 44°)
x = 44° or x = 136°


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3.
cos x = -cos 203°
cos x = -cos (180° + 23°)
cos x = -(-cos 23°)
cos x = cos 23°
x = 23° or x = (360° - 23°)
x = 23° or x = 337°


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4.
cos x = cos 181°
cos x = cos (180° + 1°)
cos x = -cos 1°
x = (180° - 1°) or x = (180° + 1°)
x = 179° or x = 181°


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5.
tan x = tan 316°
tan x = tan (360° - 44°)
tan x = -tan 44°
x = (180° - 44°) or x = (360° - 44°)
x = 136° or x = 316°


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6.
tan x = -tan 27°
x = (180° - 27°) or x = (360 - 27)°
x = 153° or x = 333°
參考: andrew


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