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標題:

數學既 more about trigonmetry

發問:

1____sin150 X cos240 / cos180 + tan135 2____sin^2 400+ cos^2 220 + tan^2 315 唔該哂 > 更新: more about trigonometry ^^打錯

最佳解答:

(sin150 X cos240) / (cos180 + tan135) = (sin30 X -cos60)/(-1 - tan45) = (1/2 X -1/2) / (-1 -1) = (-1/4)/(-2) = 1/8 sin2 400+ cos2 220 + tan2 315 = sin2 (360°+40°) +cos2 (180°+40°)+tan2 (360°-45°) = sin2 40° +cos2 40°+tan2 45° = 1+1 = 2

 

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