How do you calculate this math problem? What is this math problem?

You first draw a coordinate system, cos is the x-axis, sin is the y-axis, according to the title cos value is negative, indicating that the angle of 2 -12° is on the two or three images, that is, the left side of the x-axis, that is, 2 -12° is equal to 120°+k*360° or 240°+k*360°, and the push out = 66°+180°*k or 114°+180°*k. Because 0° 360°, when k = 0 or 1, it is 66°, 246°, 126°, 306°

As for why cosx = -1 2, x is equal to 120° + k * 360 ° or 240 ° + k * 360 °, one is to draw an image to get 120 ° or 240 °, one is to memorize it, and the other is that cos60 ° and cos-60 ° are 1 2, and the trigonometric function x is added or subtracted by 180 °, and the value of the function becomes negative.

There are many ways to memorize, and it is mainly up to you how you want to memorize.

As for the upstairs, some of them either wrote it wrong, or didn't consider the two situations, or the range was less (thinking that 0° 360° is 0° 2 -12° 360°.

Finally, the most interesting thing about math is that you never know how many answers there are until you solve the problem, and you don't know how many solutions there are after you solve the answer.

The above is a personal opinion only. As for whether it is right or wrong, whether it is reasonable or not is entirely up to the individual.

So. In [-12°,702°] we know that the angles of cosine cosa=-1 2 are 120°, 150°, 480°, 510° (by drawing an image), so it is 2 -12°=120°

So I got it.

Solution: cos(2 -12°) = -1 2 So 2 -12° = 120°+360°*k or 240°+360°*k (k is a real number).

And because 0° 360° so k = 0 or 1

So =66° or 246° or 126° or 306°

cos(2θ-12°)=-1/2

2 -12 °) in two or three limits.

That is, (2 -12°) = n 360° + 180 60° (n is an integer) = n 180° + 96° 30°

96°±30°；180°+°96° 30° (when n takes 0 and 1), i.e. =66°; 126°；246°；306°；

cos(2 -12°) = -1 2, cos60° = 1 2, so 2 -12 ° in two. Three quadrants, 2 -12° = 120° or 240°

1.That is: 2 -12° = 120°

2.That is: 2 -12° = 240°

So =66° or 126°

I can't remember, don't blame me for my mistakes! The specific formula is listed by myself, and I am not good at typography.

cos(2 -12°) = -1 2, then 2 -12° is 120° or 240° or 480° or 600°, then the solution is 66° or 126° or 246° or 306°

Because cos(2 -12°) = -1 2

So 2 -12° = 120° + 360° * k (k is a real number) and because 0° 360°

So k = 0 or 1

=66° or 256° can be obtained

The modulo of this complex number is 1

Complex number z=a+bi, then the modulo of the complex number is (a +b) substituting the original formula to know that a=1 2, b= 3 2

The modulo is (a +b )=1 4 + 3 4)=1

It's already the simplest.

You only gave a plural number, and you didn't ask what you wanted.

When the two areas of A and B are placed in a large triangle, they have a common part, such as the blank triangle on the left, the area of the big triangle is 1 2 base height, and the height is the same 2 cm, so the area of the triangle containing B is 1 2 5 2 = 5 square centimeters, and the one containing A is 1 2 3 2 = 3 square centimeters, so A is 2 square centimeters less than B.

6.The length, width and height of the cuboid are all expanded by 3 times, that is, the length, width and height are all 4 times the original, the surface area is 16 times the original, and the volume is 64 times larger, that is, the surface area is 15 times larger and the volume is 63 times larger. (fill in the blanks "15", "63").

7.A square wooden block with an edge length of 1 decimeter has a volume of 1 cubic decimeter, and it takes 1,000 such cubes to form a 1 cubic meter cube. (fill in the blanks "1", "1000").

8.The length and width of the 8 dm, 5 dm, 4 dm of the lidless cuboid bucket (the default missing top cover is made of length and width), to make this bucket at least 144 square decimeters of iron, can hold up to 160 liters of water. (Fill in the blanks "144", "160", here the volume is approximate to the volume of a cuboid bucket, 1 liter = 1 cubic decimeter).

9.The cuboid bunker is 5 meters long, wide and deep, 3 meters, meters, and the excavated soil and stone is the volume of the bunker, which is 6 cubic meters. (fill in the blank "6").

10.The cuboid tank has a volume of 400 liters, a length of 20 decimeters, a width of decimeters, and a height of 8 decimeters. (Fill in the blank "8").

1. I don't understand it, ......Isn't it a **?

21 7 15 = 45 people, that is, there are 45 people in three classes, so is the number of people in each class the same? Otherwise, you can't do it......Class 1 award: 45 1 3 = 15

Second class award: 45 1 5=9

Total number of winners: 15 + 9 + 21 = 45

Total number of students in three shifts: 45 3=135

So the number of winners is 45 135 = 1 3 (you are asking for this......The topic is so tangled ......No wonder no one answered ......)2、（1）2/5×1/4=1/10

That is, on average, the basket is filled with one-tenth of the oranges.

2) 1 1 10-4 = 6 baskets.

That is, the remaining oranges will take 6 baskets to finish.

1.First find out how many people participate, 21 is a total of 7 15, use 21 7 15 = 45 people, and find the number of people in the second class with 45 1 5 = 9 people.

For another class, use 45 1 3 = 15 people.

45 3 = 135 people.

45 135 = 1 3 people.

1 10-4 = 6 boxes.