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Is this it? Trigonometric identities.

Based on the definitions described on the previous pages, the following identity can be obtained:

Tan sin cos, cot cos sin sec 1 cos, csc 1 sin use cos 2 and sin 2 to divide cos 2 sin 2 1 respectively, you can get:

For negative angles, the six trigonometric functions of sec 2 tan 2 1 and csc 2 cot 2 1 are:

sin( sin csc( csc cos( cos sec( sec tan( tan cot( cot When two angles are added, the sum angle formula is applied:

sin( sin cos cos sin cos( cos cos sin sin tan( tan tan 1 tan tan If you encounter a double or triple angle, use the double angle formula:

sin2α＝ 2sinαcosα sin3α＝ 3sinαcos2α–sin3α

cos2α＝ cos 2α–sin 2α cos3α＝ cos 3α–3sin 2αcosα

tan 2α＝ 2tanα／1–tan 2αtan3α＝ 3tanα–tan 3α／1–3tan 2α

..."θ"It's a symbol, and the Greek alphabet is called Sita. You can think of it as the degree of a certain angle.

I feel that there is ambiguity in this question, whether to pour 50% of the whole oil for the second time or 50% of the remaining oil, according to the calculations, it should be the former case.

1/4 x+50%`x+36=108

x=96

1. Total number: 36 + 48 + 30 + 6 = 120 people;

The percentage of the number of people who have achieved individual results in the total number of participants is: 36 120 = 30% 48 120 = 40% 30 120 = 25% 6 120 = 5%.

2 Sector Statistical Drawing Method: Draw a circle and divide the 360-degree sail with a central angle into four parts according to the above proportions, and the corresponding fan of each central angle represents the number of people or their proportions of various achievements.

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(2) The number line is 3, and the coordinate system is x +y =9 8(3) origin.

4) 3 two.

Is the next one (-5) (8)-(6) 10=x-(-3) -3?

Then x=118

Accurate to the hundreds, to the fifth power 3.

, other topics are not clear.