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Give a counterexample to show whether the following proposition is false. (1) an axisymmetric figure is an isosceles triangle. (2) if a number can be divisible by 2, it can also be divisible by 4 (3) If the square of any number is greater than 0 (4), the sum of two acute angles is an obtuse angle (5). If the distance between a point and the two ends of a line segment is equal, then this point is the midpoint of the line segment
The false circle is also axisymmetric
2 false 2 cannot be divisible by 4
3 the square of 0 equals 0
4. A triangle of false 15 degrees, acute angle and acute angle
Outside the false line segment, a point on the middle line is the same as the endpoint, but not the midpoint
If 2x + 5Y = 20, and X, y are positive numbers, find the maximum value of logx + log? Use the basic inequality solution
logx+logy=logxy
Find the maximum value of XY
The root of 20 = 2x + 5Y > = 2 (10xy)
The root of 10 = 2x + 5Y > = (10xy)
square
100>=10xy
xy
The three sides of a right triangle are 6cm, 8cm and 10cm respectively. If the three sides of a right triangle are rotated for one circle to form a rotating body, what are their respective volumes?
Answer: 1) rotate on 6cm side: H = 6, r = 8
V1=πr^2h/3=π*8*8*6/3=128π
2) Rotation on 8cm side: H = 8, r = 6
V2=πr^2h/3=π*6*6*8/3=96π
3) Rotate on the 10cm side: H = H1 + H2 = 10, r = 8 * 6 / 10 = 24 / 5
V3=πr^2h/3=π*(24/5)^2*10/3=76.8π
220 V AC is input to the full bridge rectifier, and the voltmeter measures 220 V, but if the electrolytic filter capacitor is added, it will be 320 V DC. Why
Because the value measured by AC voltmeter is the effective value of AC voltage
The DC voltage after rectification and filtering is the peak value of AC, and the peak value is about 1.4 times of the average value
Set a = {1.2.3.4.5.6.7.8.9.10} to find the number of subsets containing 1
Except for 1, the other elements have two choices, which are in the target set or not,
So the answer is 2 ^ 9 = 512
Geometric line segment proof: known: point C is a point on line segment AB, and 3aC = 2Ab, D is the midpoint of AB, e is the midpoint of CB, de = 6, find the length of ab
Write an answer that I can understand
The first geometry is ignored. I am a copy of
A——D—C——E——B
∵3AC＝2AB
∴AC＝2/3AB
∴BC＝AB-AC＝AB-2/3AB＝1/3AB
∵ D is the midpoint of ab
∴BD＝1/2AB
∵ e is the midpoint of BC
∴BE＝1/2BC＝1/6AB
∴DE＝BD-BE＝1/2AB-1/6AB＝1/3AB
∴1/3AB＝6
∴AB＝18
The math group answered your question,
Let the third-order matrix a satisfy A2 = e (E is the identity matrix), but a ≠ ± E. try to prove that: (rank (A-E) - 1) (rank (a + e) - 1) = 0
It is proved that: ∵ A2 = e ∵ 0 = (A-E) (a + e) ∵ 0 = R ((a + e) (A-E)) ≥ R (a + e) + R (A-E) - 3 ∵ R (a + e) + R (A-E) ≤ 3 and & nbsp; R (a + e) + R (A-E) = R (a + e) + R (e-A) ≥ R (a + e + e-A) = R (2e) = 3 〈 R (a + e) + R (A-E) = 3. Because a ≠± e, 〈 R (a + E) ≠ 0, R (A-E) ≠ 0 〉 R (a + e), one of R (A-E) is 1 〈 (rank (A-E) - 1) (rank (a + e) - 1) = 0
3.4.12.16.24.60 which are divisors of 60 and which are multiples of 6
Multiple for integer m (except 0), can be divided by n (M / N), then M is the multiple of N. relatively speaking, n is called the factor of M. for example, 15 can be divided by 3 and 5, so 15 is the multiple of 3, and it is also the multiple of 5
If ∫ XF (x) DX = SiNx + C, then f (x) =?
∵∫xf(x)dx=sinx+C
∴xf(x)=(sinx)'=cosx
f(x)=cosx/x
What is the plural of German?
The second floor is wrong
There are three kinds of nouns indicating "a Chinese"
1. The plural of Japanese and Chinese remain unchanged
2. French, English, Dutchman, etc. change a to E
3. The plural of German, Russian, American, Indian, Italian, Korean, etc. plus s
RELATED INFORMATIONS
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- 2. In the triangle ABC, the opposite sides of the angle a.b.c. are a.b.c. and satisfy that a square plus b square plus a must be equal to C square to find the angle C
- 3. It is known that the right focus of ellipse C is F1 (1,0), M is the upper vertex of ellipse C, and O is the coordinate It is known that the right focus of the ellipse C: a squared x squared + B squared y squared = 1 (a > b > 0) is F1 (1,0), M is the upper vertex of the ellipse C, O is the coordinate origin, and the triangle OMF is an isosceles right triangle. (1) the equation for finding the ellipse C (2) whether there is a straight line L intersecting the ellipse at P and Q, and the point F is the perpendicular center of the triangle PQM, Find the equation of the straight line L; if it doesn't exist, explain the reason
- 4. In the triangle ABC, ∠ C = 90 degrees, CD ⊥ AB, ∠ B = 56 degrees, then ∠ DCA
- 5. There is a point P in the equilateral triangle ABC. The distances from point P to vertex a, B and C are 3, 4 and 5 respectively. The degree of angle APB is calculated
- 6. There is a point P in the equilateral triangle ABC. If the distances from point P to points a, B and C are 3, 4 and 5 respectively, what is the degree of ∠ APB
- 7. If AB = BC, then point B is the midpoint of AB, which is a false proposition
- 8. Please give a counter example to prove that the proposition "the same side and inner angle complement each other" is a false proposition
- 9. If the sum of two rational numbers is zero and the product is zero, then the two rational numbers () At least one of a is zero B both numbers are zero C doesn't have to be all zero D. none of the above is true It is known that the product of two numbers is - 1, one of which is 1.2 and the other is () The product of all integers whose absolute value is not greater than 4 is () If a and 3b are reciprocal, then - 9ab = () 1. It is known that the product of two numbers is - 1, one of which is 1. The other is () 2. The product of all integers whose absolute value is not greater than 4 is () 3. If a and 3b are reciprocal, then - 9ab = ()
- 10. If the rational number | a | = a, then the corresponding point of a on the number axis must be () A. Left side of origin B. The origin of the fire C. Right side of origin D. Origin or right side of origin
- 11. Proof of linear algebra Let B = (E + a) - 1 (e-A) It is proved that: (E + b) (E + a) = 2E
- 12. If two triangles have two sides equal to the middle line on the third side, are they congruent? The process of proof
- 13. Why can't edges and corners prove the congruence of triangles
- 14. Can angle prove the congruence of triangle? Why
- 15. Under what circumstances can two triangles be proved congruent
- 16. Which of the six corner elements of a triangle can determine a triangle?
- 17. As shown in the figure, in △ ABC, ab = AC, point D is the midpoint of DC, and point E is on ad. find out congruent triangles in the figure and explain why they are congruent Yeah
- 18. As shown in the figure, in △ ABC, ab = AC, point E is on high ad, find out all congruent triangles in the figure, and explain why they are congruent?
- 19. As shown in the figure, in △ ABC, ab = AC, point E is on high ad, find out all congruent triangles in the figure, and explain why they are congruent?
- 20. Two congruent triangles of similar and equal circumference