Giúp em 3 câu này với ạ, giải rõ nhé

1. x ∈( 0;$\pi$ ) sao cho cos$^{2}$2x - cos2x=0

Cho tam giác ABC (AB<AC )có ba góc nhọn , nội tiếp đường tròn tâm (O) . Hai tiếp tuyến tại B , C của đường tròn (O) cắt nhau tại M , tia AM cắt đường tròn (O) tại điểm thứ hai là D . Gọi E là trung điểm đoạn thẳng AD , tia CE cắt đường tròn tâm O tại điểm thứ hai là F . C/m góc MOC = góc MEC

Anh chị nào giải công thức em với để hiểu kiến thức được ?

Tìm lỗi sai LÀM + GIẢI THÍCH giúp mk vs HAY NHẤT ạ Cảm ơn

Vẽ anime nữ (kiểu cổ trang ý :>) Đẹp nhé

Hôm nay trời mưa cũng như tâm trạng trong lòng tôi ngay lúc này ;-; Đề : Vẽ đậu mầm bùn /chibi bùn / anime bùn /calli : Buồn .

Giúp mình vs ạ mik đang cần gấp

Chọn đáp án đúng 21. Almost everyone _______ for home by the time we arrived. A. leave B. left C. leaves D. had left 22. By the age of 25, he ______ two famous novels. A. wrote B. writes C. has written D. had written 23. When her husband was in the army, Mary ______ to him twice a week. A. was reading B. wrote C. was written D. had written 24. I couldn't cut the grass because the lawn mower ______ a few days previously. A. broke down B. has been broken C. had broken down D. breaks down 25. I have never played badminton before. This is the first time I _____ to play. A. try B. tried C. have tried D. am trying 26. Since _______, I have heard nothing from him. A. he had left B. he left C. he has left D. he was left 27. After I _______ lunch, I looked for my bag. A. had B. had had C. have has D. have had 28. By the end of next year, George _______ English for two years. A. will have learned B. will learn C. has learned D. would learn 29. The man got out of the car, ________ round to the back and opened the book. A. walking B. walked C. walks D. walk 30. Henry _______ into the restaurant when the writer was having dinner. A. was going B. went C. has gone D. did go 31. He will take the dog out for a walk as soon as he ______ dinner. A. finish B. finishes C. will finish D. finishing 32. I will be glad if he _______ with us. A. had gone B. did go C. went D. goes 33. Ask her to come and see me when she _______ her work. A. finish B. has finished C. finished D. finishing 34. Turn off the gas. Don't you see that the kettle ________? A. boil B. boils C. is boiling D. boiled 35. Tom and Mary ______ for Vietnam tomorrow. A. leave B. are leaving C. leaving D. are left 36. He always ________ for a walk in the evening. A. go B. is going C. goes D. going 37. Her brother ______ in Canada at present. A. working B. works C. is working D. work 38. I ______ to the same barber since last year. A. am going B. have been going C. go D. had gone 39. Her father ______ when she was a small girl. A. dies B. died C. has died D. had died 40. Last week, my professor promised that he ________ today. A. would come B. will come C. comes D. coming

Một cửa hàng ngày đầu bán được 120 m vải ngày 2 bán đc gấp 3 lần số mét vải trong ngày đầu. Hỏi cửa hàng đã bán đc bn m vải trong 2 ngày