昨晚的回答不知何故又被隱了, 簡單回答吧. 令 x = cos(3π/5) 則 cos(9π/5) = 4x^3 - 3x cos(6π/5) = 2x^2 - 1 cos(9π/5) + cos(6π/5) = 0 即 4x^3 + 2x^2 - 3x - 1 = (x+1)(4x^2 - 2x - 1 ) = 0. 因 π/2 < 3π/5 < π, 故 0 > cos(3π/5) > -1 故 cos(3π/5) = (1-√5)/4.
...sentence with He(subj) Add the original verb after it= come ori.verb That's not the past tense as it is...: make, let, have. eg:-usage of let eg:- let is to allow sb to do sth eg:- Let them splash around...
...day and built his house with bricks. ---A big bad wolf came along, saw the two little pigs and wanted to eat them. He chased the 2 pigs that hid in...
... the work experience u gained there? were u saying u like to do customer service as a life-long profession? Secondly: Grade D...
... a very Manson-like cult (really, is there anything more to say?) and, well, it comes with a lot of pre-publication “buzz.” So hear this: The Girls...
1.would go; ----would not be;---past tense of will=would; indirect speech 2. had given-----past perfect 3.was caught------past, passive
...when adv; at what time; on what occasion;- eg:-"When" can you come ? eg:-"When" did that happen ? eg:-I don't...can I help her "when" she won't listen to me ?
...that I had agreed ! eg:- Come whenever you will (wish to come ). ---Would replaces will to show future in the past:- eg:-I wonder...
..., "which" they had always wanted to visit. 本句應使用關係代名詞which，因為在形容詞子句...代名詞性質，如：This is the place where he comes "from."（where與介系詞from連用，在此當作關係代名詞...
