If (1 + cos2a) / Sina = 2, then cosa Sina=

Cos (2 α) = 1-2 (sin α) ^ 2 is substituted into the above formula, and becomes a binary linear equation about sin α. Solve Sina, and then get cosa according to Sina ^ 2 + cos ^ 2 = 1, and then come out

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1. What are the integer part of 2-radical 3 and the decimal part of 2 + radical 3
2. It is known that the integer part of 2-radical 7 is a and the decimal part is B. try to find the value of B (AB + 6)
3. What are the integer and decimal parts of root 51! As above
4. Given that the integer part of √ 5 is a and the decimal part is B, find the value of a (√ 5-b)
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6. Given that the integer part of root 13 is a and the decimal part is B, find the value of ab
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9. Given that a is the integral part of √ 13 and B is the fractional part of √ 13, find the value of A-B?
10. Given that the decimal parts of 6 + radical 11 and 6 - radical 11 are a and B, find the value of ab
11. It is known that → a = (COSA, Sina), → B = (CoSb, SINB), 0 is less than B, less than a, less than Pai (1) If | → a - → B | = radical 2, prove: → a perpendicular to the foot → B. (2) let → C = (0,1), if → a + → B = → C, find the value of a and B
12. It is proved that sinc = Sina + SINB / cosa + CoSb To be more specific, I'm just beginning to learn it. I can't get around it. Don't cross too many troublesome steps~ thank you
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14. （2010-1）+（2000-2）+（1999-3）+.+（1002-1000）
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16. 2004 × 2002 / 2003 (simple calculation)
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