There are 50 students in our class, including 24 boys and 26 girls. What's the percentage of boys in the class? Girls

There are 50 students in our class, including 24 boys and 26 girls. What's the percentage of boys in the class? Girls

12 / 25 / 12
1. The value of COS square 22.5-sin square 22.5, sin70 degree, cos25 degree - cos70 degree, sin25 degree, tan10, tan20 + root 3 (tan10 + tan20)
4. The function y = 2Sin (Pie / 3-x) - cos (Pie / 6 + x) x belongs to the minimum value of R
5. What is the period of the function y = cos ^ 2x-1 / 2
6. Let a = sin14 + cos14, B = sin16 + cos16, C = root 6 / 2, then the relationship between ABC and its size
Write clear process, good additional score! Thank you!
1. Cos ^ 2 22.5 ° - Sin ^ 2 22.5 ° = cos 45 ° = (radical 2) / 2, using the formula cos 2x = cos ^ 2 x-sin ^ 2 x;
2. Sin70 ° cos25 ° - cos70 ° sin25 ° = sin (70 ° - 25 °) = sin45 ° = (radical 2) / 2, using the formula sin (X-Y) = sinxcosy cosxsiny;
3. Because Tan 30 ° = (Tan 10 ° + Tan 20 °) / (1-tan 10 ° Tan 20 °), root 3 (Tan 10 ° + Tan 20 °) = 1-tan 10 ° Tan 20 °,
Therefore, Tan 10 ° Tan 20 ° + root 3 (Tan 10 ° + Tan 20 °) = 1;
4. Because (π / 3-x) + (π / 6 + x) = π / 2, so
y=2sin(π/3-x)-cos(π/6+x)=2sin[π/2-(π/6+x)]-cos(π/6+x)=cos(π/6+x)
So the minimum value of the function is - 1;
5. Y = cos ^ 2x-1 / 2 = (cos2x + 1) / 2-1 / 2, so the period of the function is π;
6. A = sin14 ° + cos14 ° = sin14 ° + sin76 ° = 2sin45 ° cos31 ° = (radical 2) cos31 °,
B = sin16 ° + cos16 ° = sin16 ° + sin74 ° = 2sin45 ° cos29 ° = (radical 2) cos29 °,
C = [(root 2) (root 3)] / 2, then the size relationship of a, B and C is: a
There are 24 girls in class 51, 4 less than boys. Boys and girls account for a few percent of the class
7 grams of sugar is dissolved in 100 grams of water. What's the percentage of sugar? What's the percentage of sugar in the water?
It takes 8 hours for Master Li and 7 hours for Master Zhang to make 20 identical parts. How many hours does it take for each of the two masters to make a part
It takes 12 days to build a 10 yard long flood dike. How many parts of the dike are built every day? How many parts of the dike are built every meter
1. There are 24 girls in class 51, 4 less than boys. Boys and girls account for a few percent of the class
The proportion of male students in the class: (24 + 4) / (24 + 4 + 24) = 7 / 13
The proportion of female students in the class: 24 / (24 + 4 + 24) = 6 / 13
2. 7 grams of sugar is dissolved in 100 grams of water. What's the percentage of sugar? What's the percentage of sugar in the water
Sugar is water: 7 / 100 = 7 / 100
The proportion of sugar in sugar water: 7 ÷ (7 + 100) = 7 / 107
3. It takes 8 hours for Master Li and 7 hours for Master Zhang to make 20 identical parts. How many hours does it take for each of the two masters to make a part
Master Li needs 8 △ 20 = 2 / 5 hours to make a part
Master Zhang needs 7 △ 20 = 7 / 20 hours to make a part
4. It takes 12 days to build a 10 yard long flood dike. How many parts of the dike are built every day? How many parts of the dike are built every meter
The average daily cost of building this section of levee is: 1 / 12 = 1 / 12
It takes 12 days to divide the length of each meter (what's the length of a 10 yard long levee here?)
Simplification (1) sin π / 8cos π / 8 (2) Tan 81 ° - cot 54 ° / 1 + Tan 81 ° cot 54 ° (3) sin 70 ° cos 25 ° - Sin 25 ° cos 70 °
The solution sin π / 8cos π / 8 = 1 / 2 (2Sin π / 8cos π / 8) = 1 / 2Sin π / 4 = √ 2 / 4sin70cos25-sin25cos70 = sin (70-25) = sin45 = √ 2 / 2tan81-cot54 / (1 + tan81cot54) = (tan81-tan36) / (1 + tan81tan36) = Tan (81-36) = tan45 = 1
The number of male students in a class is 7 / 8 of that of female students. What is the percentage of male students in the class?
7/15
sin70°sin65°-sin20°sin25°
sin70°sin65°-sin20°sin25°
=cos20°cos25°-sin20°sin25°
=cos(20°+25°)
=cos45°
=Root 2 / 2
There are 18 boys and 22 girls in class 5 (1). Boys and girls account for a few percent of the class
Help,
Male: 18 / (18 + 22) = 9 / 20
Female: 1-9 / 20 = 11 / 20
The total pool is 18 + 22 = 40, and the ratio of each girl to the whole class is 1 / 40
Sin70 degrees sin65 degrees - sin20 degrees sin25 degrees equals?
70 degree decomposition is 25 + 45, 65 decomposition is 20 + 45. Using sin (a + b) expansion, we can get the result
Sin70 degrees sin65 degrees - sin20 degrees sin25 degrees
=Cos 20 degrees cos 25 degrees sin 20 degrees sin 25 degrees
=Cos (20 degrees + 25 degrees)
=Cos45 degree
=√ 2/2
Original formula = sin70 ° cos25 ° - sin25 ° cos70 °
=sin（70°-25°）
=sin45°
=√2/2
=cos20cos25-sin20sin25
=cos45
=√2/2
The ratio of male to female students is 5:4, the number of female students accounts for a few percent of the class, and the number of male students more than female students accounts for ()% of the class
For the process, fill in the percentage before the last blank
(1) If there are 5x boys and 4x girls in the class, there are 9x girls in the class, so the number of girls in the class is 4x / 9x = 4 / 9. (2) because there are 5x boys and 4x girls in the class, there are more boys than girls. (5-4) x = X and because there are 9x girls in the class, there are more boys than girls in the class
Sin70 cos 25 - sin20 sin25 = why sin (70 - 25) = sin45
Sorry, I'm too busy on Sunday now. I don't have time. This is based on the sum and difference formula sin (a-b) = sinacosb cosasinb, where sin20 ° = cos70 °; sin70 ° cos25-sin20 ° sin25 ° = sin70 ° cos25-cos70 ° sin25 ° = sin (70 ° - 25 °) = sin45 ° = √ 2 / 2. Please click [ok
Sin (a-b) = sinacosb sinbcosa, sine formula of difference angle