Rút gọn bài sau về sin
U.sin(θ-2π/3)-U.sin(θ+2π/3)
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1. that chọn 2
2 think chọn 1
3 other chọn 2
4 weather chọn 2
6 earth chọn 2
5 theatre chọn 1
7 feather chọn 2
8 three chọn 1
9 thieves chọn 1
10 there chọn 2
11 although chọn 1
12 thank chọn 1
13 brother chọn 2
14 month chọn 2
15 healthy chọn 2
16 breath chọn 1
17 breathe chọn 1
18 them chọn 2
19 thirsty chọn 1
20 clothe chon 1
1. that /ð/ 6. earth /θ/ 11. although /ð/ 16. breath /θ/
2. think /θ/ 7. feather /ð/ 12. thank /θ/ 17. breathe /ð/
3. other /ð/ 8. three /θ/ 13. brother /ð/ 18. them /ð/
4. weather /ð/ 9. thieves /ð/ 14. month /θ/ 19. thirsty /θ/
5. theatre /θ/ 10. there /ð/ 15. healthy /θ/ 20. clothe /ð/
1. that /ð/ 6. earth /θ/ 11. although /ð/ 16. breath /θ/
2. think /θ/ 7. feather /ð/ 12. thank /θ/ 17. breathe /ð/
3. other /ð/ 8. three /θ/ 13. brother /ð/ 18. them /ð/
4. weather /ð/ 9. thieves /ð/ 14. month /θ/ 19. thirsty /θ/
5. theatre /θ/ 10. there /ð/ 15. healthy /θ/ 20. clothe /ð/
I. How is th pronounced in the following words? Circle the correct option
1. that /θ/ /ð/ 6. earth /θ/ /ð/ 11. although /θ/ /ð/ 16. breath /θ/ /ð/
2. think /θ/ /ð/ 7. feather /θ/ /ð/ 12. thank /θ/ /ð/ 17. breathe /θ/ /ð/
3. other /θ/ /ð/ 8. three /θ/ /ð/ 13. brother /θ/ /ð/ 18. them /θ/ /ð/
4. weather /θ/ /ð/ 9. thieves /θ/ /ð/ 14. month /θ/ /ð/ 19. thirsty /θ/ /ð/
5. theatre /θ/ /ð/ 10. there /θ/ /ð/ 15. healthy /θ/ /ð/ 20. clothe /θ/ /ð/
1. A 2.C 3.B 4.A 5.D
1.2, 2.1, 3.2, 4.2, 5.1, 6.1, 7.2, 8.1, 9.1, 10.2, 11.2, 12.1, 13.2, 14.1, 15.2, 16.1, 17.1, 18.2, 19.1, 20.2
\(sin^6\left(\pi+x\right)=sin^6x,cos^6\left(x-\pi\right)=cos^6\pi\\ sin^4\left(x+2\pi\right)=sin^4x,sin^4\left(x-\dfrac{3\pi}{2}\right)=cos^4x,cos^2\left(x-\dfrac{\pi}{2}\right)=sin^2x.\)
Khi đó \(A=sin^6x+cos^6x-2sin^4x-cos^4x+sin^2x\\ =\left(sin^2x+cos^2x\right)^2-3sin^2x.cos^2x\left(sin^2x+cos^2x\right)-\left(sin^4x+cos^4x\right)-sin^4x+sin^2x\\ =1-3sin^2x.cos^2x-\left[1-2sin^2x.cos^2x\right]-sin^2x.\left(sin^2x-1\right)\\ =1-3sin^2x.cos^2x-1+2sin^2x.cos^2x+sin^2x.cos^2x\\ =0\)
Lớp 8 có này ?? :D ??