In the triangle ABC, A.B.C is the opposite side of the angle A.B.C respectively, and satisfies the square of B + the square of C - the square of a = BC 1 In the triangle ABC, A.B.C is the opposite side of the angle A.B.C, and satisfies the following condition: the square of B + the square of C - the square of a = BC 1. Find the value of angle A 2. If a = root 3, let the size of angle B be x and the perimeter of triangle ABC be y, then find the maximum value of y = f (x) Thank you very much

In the triangle ABC, A.B.C is the opposite side of the angle A.B.C respectively, and satisfies the square of B + the square of C - the square of a = BC 1 In the triangle ABC, A.B.C is the opposite side of the angle A.B.C, and satisfies the following condition: the square of B + the square of C - the square of a = BC 1. Find the value of angle A 2. If a = root 3, let the size of angle B be x and the perimeter of triangle ABC be y, then find the maximum value of y = f (x) Thank you very much

(1) According to the cosine theorem: cosa = (B & # 178; + C & # 178; - A & # 178;) / 2BC = 1 / 2, ∠ a = 60 & # 186;

Given the function f (x) = x & # 178; + 2x + 4 / x, X ∈ [1, + ∞], find the minimum value of F (x)

f(x)=(x²+2x+4)/x
F (x) = x + 4 / x + 2 basic inequality x + 4 / x > = 2 √ (x * 4 / 4) = 4
When x = 4 / x, there is a minimum of 6
That is, when x = 2, there is a minimum value of 6

What is the position relationship between the circumscribed circle of a right triangle and the circle whose diameter is the center line on the hypotenuse of the right triangle

The circumscribed circle of a right triangle is inscribed with the circle whose diameter is the center line on the hypotenuse of the right triangle
You can see it by drawing a picture
Or the distance between the centers of a circle is equal to the difference between the radii

Given the complete set u = {x ≤ 4}, set a = {X - 2 < x < 3}, B = {X - 3 ≤ x ≤ 2}, find (Cu A) ∪ B
It's better to have a number axis

According to the meaning of the title,
Cu A = {x ≤ - 2 or 3 ≤ x ≤ 4}
therefore
(Cu A) ∪ B = {x ≤ - 2 or 3 ≤ x ≤ 4} ∪ {X - 3 ≤ x ≤ 2}
={x 3 ≤ x ≤ 4 or X ≤ - 2}

As shown in the figure, in △ ABC, ∠ BAC = 108 ゜, ab = AC, BD bisects ∠ ABC, intersects AC with D, and proves: BC = CD + ab

Method 1: in △ abd and △ EBD, ab = EB, abd = ebdbd = BD, be = Ba, De, ≌ △ EBD (SAS), ≌ △ BAC = ≌ bed = 108 °, ab = EB, ∨ Dec = 72 ゜, ∨ AB = AC, ≌ C = ABC

If the real number x satisfies the condition (X & # 178; - 5x + 6) &# 178; + | X-2 | = 0, find the value of X and write the square root of X

（x²-5x+6）²+|x-2|=0
Then x ^ 2-5x + 6 = (X-2) (x-3) = 0 and X-2 = 0
So x = 2
So the second power of 2 is 4

As shown in the figure, in △ ABC, the vertical bisector of ∠ C = 90 ° AB intersects AC at D, and the perpendicular foot is e. if ∠ a = 30 ° de = 2, the degree of ∠ DBC is______ The length of CD is______ ．

∵ De is the vertical bisector of AB, ∵ ad = BD, ≌ ADB is isosceles triangle, ∵ DBA = ∠ a = 30 °, ∵ CBD = 60 ° - 30 ° = 30 °, ≌ RT △ CDB ≌ RT △ DEB, ≌ CD = de = 2

A mathematical problem (available equation, arithmetic, equation with one variable equation) for detailed solutions!
The sixth grade students are divided into two groups: group A and group B. the number ratio of group A and group B is 7:3. Later, due to the need of labor, 30 students were sent from group A to group B. in this way, the number ratio of group A and group B becomes 3:2?

7/10-3/5=1/10
30/(1/10)=300
Equation: let x people in total,
7/10X-3/5X=30
X=300

How to calculate the acceleration of 5 segments displacement with the successive difference method of high school physics~~~

Let S1, S2, S3, S4, S5 start from the minimum segment, and the corresponding time of each segment is t. the successive difference method is to use even segments, and S1 or S3 or S5 can be omitted. The method is: if S1 is not needed, acceleration a = [(s4-s2) + (s5-s3)] / (4T ^ 2) if S3 is not needed, acceleration a = [(S4-S1) + (s5-s2)] / (6T ^ 2)

1. Congcong cleaned some potatoes in a cylindrical container with a bottom radius of 20cm. After all the potatoes were immersed in water, the water depth was 30cm. After taking out the potatoes, the water surface dropped by 3cm. Can you find out the volume of potatoes?
2. Jingjing family put a stone in a cylindrical fish tank with a bottom diameter of 20cm, and the water surface rose from 26cm to 28cm?
3. A cylindrical well, its wellhead circumference is 3.14m, well depth is 18m, usually the depth of water storage is 8 / 9 of the well depth. How many cubic meters of water storage is this well usually?
4. If a section of cylindrical wood is cut into two sections, its surface area will increase by 6.28 square meters. If it is split into two and a half cylinders along the diameter of the bottom, its surface area will increase by 40 square meters. Find the surface area of this section of wood

The volume calculation formula of the cylinder is: the area of the bottom x is high. Subtract the volume of the cylinder when you put the potato, and the volume of the cylinder after you take out the potato is equal to the volume of the potato. The volume of the cylinder when you put the potato: 3.14 times the square of 20 (now the area of the bottom of the cylinder is calculated) times 30, which is equal to 37680 cubic centimeters