The number of boys in a class is 5 / 7 of the number of girls. What is the ratio of boys to girls? What is the percentage of boys in the class and what is the percentage of girls in the class

The number of boys in a class is 5 / 7 of the number of girls. What is the ratio of boys to girls? What is the percentage of boys in the class and what is the percentage of girls in the class

The ratio of male to female students is 5:7;
Boys account for 5 / 12 of the class;
Girls account for 7 / 12 of the class
Using sum (difference) angle formula: sin70 degree cos25 degree - sin20 degree sin25 degree
That small circle can't be typed by mobile phone, so we have to use Chinese "degree" to express it!
Using sin20 ° = cos (90 ° - 20 °) = cos70 °, then: the original formula = sin70 ° cos25 ° - cos70 ° sin25 ° = sin (70 ° - 25 °) = sin45 ° = √ 2 / 2
There are 18 boys in class 5 (1), 5 less than girls. How many percent of the class are boys and girls?
1. Female: 18 + 5 = 23
2. How many parts of the class are boys: 18 ÷ (18 + 23) = 18 / 41
3. How many parts of the class are female students: 1-18 / 41 = 23 / 41
The sum (difference) angle formula is used to find the following values: (1) sin 70 ° cos 25 ° - Sin 20 ° sin 25 °; (2) cos ^ 2 15 ° - Sin ^ 2 15 °;
sin70°cos25°-sin20°sin25°=sin70°cos25°-cos70°sin25°=sin(70°-25°)=sin45°=(√2)/2
cos^2 15°-sin^2 15°=cos(2*15°)=cos30°=(√3)/2
1. Sin70 = sin20, sin70cos25-sin20sin25 = cos20cos25-sin20sin25 = cos (20 + 25) = radical 2 / 2
2. Cos ^ 215 = 1-sin ^ 215, so cos ^ 215-sin ^ 215 = 1-2sin ^ 215 = cos30 = root 3 / 2
There are 14 girls in class 52, 18 more boys than girls
14 + 18 = 32 (person)
32 + 14 = 46 (person)
Female: 14 & # 10135; 46 = 14 / 46
Male: 32 & # 10135; 46 = 32 / 46
What is sin70
sin(70) = 0.77389068155789
If 2cos10 ^ 2-1 = cos20 and cos10 ^ 2 = 0.5cos20.5, then 2-cos10 ^ 2 = 1.5-0.5cos20 (3-sin70) / (2-cos10 ^ 2) = (3-cos20) / (1.5-0.5cos20) = 2
There are 56 students and 29 girls in class 51 of a certain school. What's the percentage of girls in the class? What's the percentage of boys in the class?
Girls make up 29 / 56 of the class and boys 27 / 56 of the class
High school mathematics calculation should have formula
Even a mathematical problem: the diameter of the mandrel is 5mm, the thickness of the film is 0.1mm, and the width of the film is 60mm
Radius r = (2.5 + 0.1) mm, perimeter 1 = 2 π r = 2 π (2.5 + 0.1) mm
Radius r = 2.5 + 0.1 + 0.1, perimeter 2 = 2 π (2.5 + 0.1 + 0.1) mm
.
Membrane length = perimeter 1 + perimeter 2=
If 2 π is put forward, it is obviously an arithmetic sequence. The first term A1 = 2.6, and the tolerance D is 0.1
an=a1+(n-1)*d=2.6+0.1(n-1)=0.1n+2.5
Membrane length = (a1 + an) * n / 2
= (2.6+0.1n+2.5)*n/2
=(5.1+0.1n)*n/2
Substituting n = 200
Membrane length = 2510 mm = 2.51 M
There are 48 students in class 54, including 29 boys. What is the percentage of girls in the class? What is the percentage of boys in girls? What is the percentage of girls in boys?
One (48-29) / 48 = 19 / 48
Two 29 / (48-29) = 29 / 19
Three (48-29) / 29 = 19 / 29
What is the minimum value of the function y = (x ^ 2 + 5) / root x ^ 2 + 4? It's better to use the basic inequality solution instead of your own
What's the name of the first floor
In addition, X & sup2; + 4 = K & sup2;
The original formula is k square + 1 / K
=K+1/K
Because K belongs to 2 to positive infinity
The lowest point of the original formula is (1,2)
So it increases monotonically in the range of K
Then when k is 2, X is 0, and the minimum value is 2.5