There are 21 boys and 24 girls in class 6 (1). The simplest integer ratio of the number of men and women is (), and the number of boys accounts for () of the total number of the class () There are 21 boys and 24 girls in class 6 (1). The simplest integer ratio of the number of men and women is (). The number of boys accounts for () of the total number of the class (). The number of boys is () less than that of girls Write out two ratios whose ratios are both 0.75 and make up the ratio () The radius of the big circle is three times that of the small circle. The perimeter ratio of the big circle to the small circle is (), the area ratio is (), and the diameter ratio is () The factor of 15 is () and the factor of 15 forms a proportion () 9 △ () = 1.5 = 9 of 4: () = (): 12 = 18 () = (): () It is known that 3:4 = 6; 8 if 6 in the formula is changed to 9, then 8 should be changed to () Match one of the following numbers so that the four numbers can form a proportion 8. 32, 16 and () 3 / 4, 12, 3 / 5 and () Judgment questions The quotient of the number a divided by the number B is 2 and 1 / 2, and the ratio of the number a to the number B is 5:2 () The former and the latter of the ratio are multiplied by the same number (except 0), and the ratio remains unchanged () The area of the diameter triangle is fixed, and the length of the two right angles is inversely proportional () The number of tiles is fixed, and the area of each tile is in direct proportion () If 3A = 4B (AB is not 0), then a: B = 3:4 Fill in the blanks On a map with a scale of 1:5000000, the distance between Fuzhou and Shanghai is 16cm, and the actual distance between Fuzhou and Shanghai is about () km Given that x = 5 / 5 y, then x and Y become () (fill in the proportion or disproportion) One is that the attendance rate of a class is 90%, and the ratio of attendance to absence is () The circumference of a rectangle is 96cm, and the ratio of length to width is 5:3. The length and width of the rectangle are (() cm, () cm) A triangle, its three internal angle degree ratio is 1:3:2, this triangle is () triangle For a journey of 400 kilometers, car a takes 5 hours and car B takes 8 hours. The speed ratio between car a and car B is () ① 5:8 ② 8:5 ③ 1 / 8

There are 21 boys and 24 girls in class 6 (1). The simplest integer ratio of the number of men and women is (), and the number of boys accounts for () of the total number of the class () There are 21 boys and 24 girls in class 6 (1). The simplest integer ratio of the number of men and women is (). The number of boys accounts for () of the total number of the class (). The number of boys is () less than that of girls Write out two ratios whose ratios are both 0.75 and make up the ratio () The radius of the big circle is three times that of the small circle. The perimeter ratio of the big circle to the small circle is (), the area ratio is (), and the diameter ratio is () The factor of 15 is () and the factor of 15 forms a proportion () 9 △ () = 1.5 = 9 of 4: () = (): 12 = 18 () = (): () It is known that 3:4 = 6; 8 if 6 in the formula is changed to 9, then 8 should be changed to () Match one of the following numbers so that the four numbers can form a proportion 8. 32, 16 and () 3 / 4, 12, 3 / 5 and () Judgment questions The quotient of the number a divided by the number B is 2 and 1 / 2, and the ratio of the number a to the number B is 5:2 () The former and the latter of the ratio are multiplied by the same number (except 0), and the ratio remains unchanged () The area of the diameter triangle is fixed, and the length of the two right angles is inversely proportional () The number of tiles is fixed, and the area of each tile is in direct proportion () If 3A = 4B (AB is not 0), then a: B = 3:4 Fill in the blanks On a map with a scale of 1:5000000, the distance between Fuzhou and Shanghai is 16cm, and the actual distance between Fuzhou and Shanghai is about () km Given that x = 5 / 5 y, then x and Y become () (fill in the proportion or disproportion) One is that the attendance rate of a class is 90%, and the ratio of attendance to absence is () The circumference of a rectangle is 96cm, and the ratio of length to width is 5:3. The length and width of the rectangle are (() cm, () cm) A triangle, its three internal angle degree ratio is 1:3:2, this triangle is () triangle For a journey of 400 kilometers, car a takes 5 hours and car B takes 8 hours. The speed ratio between car a and car B is () ① 5:8 ② 8:5 ③ 1 / 8

There are 21 boys and 24 girls in class 6 (1). The simplest integer ratio of male to female is (7:8). The number of boys accounts for (7 / 15) of the total number of the class, and the number of boys is less than that of girls (12.5%)
Write the two ratios of 0.75 and make up the proportion (3:4 = 9:16)
The radius of the big circle is three times that of the small circle. The perimeter ratio of the big circle to the small circle is (3:1), the area ratio is (9:1), and the diameter ratio is (3:1)
The factors of 15 are (1,3,5,15), and the factors of 15 form a proportion (1:3 = 5:15)
9 ÷ (6) = 1.5 = 9 out of 4: (2 / 3) = (18): 12 = 27 out of 18) = (3): (2)
It is known that 3:4 = 6; 8 if 6 in the formula is changed to 9, then 8 should be changed to (12)
Add a number to each of the following numbers so that the four numbers can form proportions 8, 32, 16 and (4)
3 / 4, 12 / 5 and (15)
Judgment questions
The quotient of number a divided by number B is 2 and 1 / 2, and the ratio of number a to number B is 5:2 (√)
The former and the latter of the ratio are multiplied by the same number (except 0), and the ratio remains unchanged (√)
The area of the diameter triangle is fixed, and the length of the two right angles is inversely proportional (√)
The number of floor tiles is fixed, and the area paved is in direct proportion to the area of each tile (√)
If 3A = 4B (AB is not 0), then a: B = 3:4 (×)
Fill in the blanks. On a map with a scale of 1:5000000, the distance between Fuzhou and Shanghai is 16cm. The actual distance between Fuzhou and Shanghai is about (900km)
Given that x = 5 / 5 y, then x and y are (inversely proportional) (fill in what proportion or out of proportion)
One is that the attendance rate of a class is 90%, and the ratio of attendance to absence is (9:1)
The circumference of a rectangle is 96cm, and the ratio of length to width is 5:3. The length and width of the rectangle is (30cm) and (18cm) a triangle, and the ratio of its three internal angles is 1:3:2. The triangle is (right angle) triangle
For a journey of 400 kilometers, car a takes 5 hours and car B takes 8 hours. The speed ratio of car a and car B is (2) 5:8, 8:5, 1:5 of 8
-Cos 20 ° = - Sin 70 ° why?
There is a theorem sin a = cos B, where b = 90 ° - A. This is just a minus sign
As for the theorem, you can draw a triangle and compare it
For example, RT △ ABC ∠ C = 90, a = 3, B = 4, C = 4, then SIA ∠ a = 0.6, cos ∠ B = 0.6, which is verified
Isn't ∠ a equal to 90 °～ B
Didn't your teacher say that? I know all about it
There are 32 boys and 28 girls in class 5 (2). What percentage of boys are girls? How many times are boys?
28/32=7/8
So girls make up 7 / 8 of boys
32/28=8/7
So boys are 8 / 7 times as many as girls
Sin20 = cos70, right
Yes, just use a calculator
sin20°=cos70°
Sin20 ° = cos70 ° remember to add degrees!
It is sin20 ° = cos70 °
Yes
According to the induction formula
There are 47 students in class 51 of Yucai primary school, among whom 21 are girls, and some of them are boys
Boys: 47-21 = 26
26÷47=26
——(26 out of 47)
Forty-seven
Can cos 70 ° and sin 20 ° be converted to each other?
If it can be converted, under which circumstances can it be converted?
Interchangeable
In a right triangle, the sum of two acute angles is 90 degrees, so cos70 = sin (90-70 degrees). This is a scientific conclusion
Cos70 is equal to sin20 in numerical value. Question: under what circumstances can it be converted?
There are 21 girls in class 1 of grade 5, 3 less than boys. What's the percentage of girls in boys? What's the percentage of boys in the class?
7/8 8/15
sin20*cos70+sin10*50
sin20cos70+sin10sin50
=(sin20)^2-1/2(cos60-cos40)
=(1-cos40)/2-(cos60-cos40)/2
=(1-1/2)/2
=1/4
If I don't do it, I think it's wrong
Is it sin20 * cos70 + sin10 * sin50????
The number of male students in Grade 6 is 710 times that of female students, so the number of male students accounts for & nbsp; & nbsp; & nbsp; & nbsp; & nbsp;) of the whole grade
Suppose the number of boys is 7, then the number of girls is 10, the number of students in the whole grade is 7 + 10 = 17, 7 △ 17 = 717
Cos70 degree cos25 degree + sin110 degree cos65 degree =?
Cos25 = sin65
Sin110 = sin (180-110) = sin70
So:
Cos 70, cos 25, sin 110, cos 65
=cos70sin65+sin70cos65
=sin(70+65)=sin135
=sin(180-135)=sin45
=(2 under root) / 2