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In ABC triangle, a = 2bcosc, judge what triangle is
According to the cosine theorem: COSC = (A & sup2; + B & sup2; - C & sup2;) / 2Ab a = 2bcosc
∴(a²+b²-c²)/2ab =a/2b
‖ B & sup2; = C & sup2; ∵ ABC triangle ‖ B = C
A triangle is an isosceles triangle
In the triangle ABC, it is known that a-square-c-square = AC root 3bC, and a, B, C are in equal proportion sequence, then a is obtained
a^2-c^2=ac-√3bc,b^2=ac
A ^ 2-B ^ 2-C ^ 2 = - √ 3bC
So cosa = (b ^ 2 + C ^ 2-A ^ 2) / (2BC) = √ 3 / 2
A=π/6
In △ ABC, a, B, C are in equal proportion sequence, and a & # 178; - C & # 178; = AC BC, find a and bsinb / C
a. If B and C are in equal proportion sequence, then:
b²=ac
Because: A & # 178; - C & # 178; = AC BC, then:
a²－c²=b²－bc
b²＋c²－a²=bc
cosA=(b²＋c²－a²)/(2bc)=1/2
A=60°
Bsinb / C [B & # 178; = AC, then: B / C = A / b]
=(a/b)sinB
=a(sinB/b)
=a(sinA/a)
=sinA
=√3/2
If LGA, LGB and LGC are equal difference sequence, then the relationship among a, B and C is equal
LGA, LGB and LGC form arithmetic sequence
2lgb=lga+lgc
lgb^2=lgac
b^2=ac
So it's an equal ratio sequence
When a moving object moves in a straight line, the average speed in 1s & nbsp; is 3m / s, the average speed in 2S & nbsp; and 3S & nbsp; is 6m / s, and the average speed in 4S & nbsp; is 5m / s, then the average speed of the moving object in 4S is 3m / s______ ．
The average velocity in 1s & nbsp; is 3m / s, the average velocity in 2S and 3S & nbsp; is 6m / s, and the average velocity in 4S & nbsp; is 5m / s, so the displacement in 1s & nbsp; is 3M, the displacement in 2S is 6m, the displacement in 3S is 6m, the displacement in 4S is 5m, so the total displacement in the first 4S is: x = 3 + 6 + 6 + 5 = 20m, so the average velocity of moving object in 4S is. V = XT = 20ms, 4S = 5m / s, so the answer is: 5m / s
Using VB to program the sum of natural numbers from 1 to 100
dim i as integer
dim sum as integer
i = 1
Method 1
do while i 100
sum = sum + i
i = i + 1
loop
Method 3
do
sum = sum + i
i = i + 1
loop while i < 100
If no matter what the value of K is, x = - 1 is the solution of the equation (KX + a) about X, 2 = (- x-bk) \ - 3, find the value of ab
Substituting - 1 into! Gets: (A-K) / 2 = (1-bk) / - 3
3A-2BK=-2+3K
So 3A = - 2
-2BK=3K
A=-2/3 B=-3/2
AB=1
The distance from a point on the number axis to the origin is 5 and half, so what is the number represented by this point?
If there is a point on the number axis whose distance from the origin is 5 and half, then the number represented by this point is 5 and half or - 5 and half
A mathematical problem about proportion!
In order to build a teaching building in a primary school, cement, yellow sand and stones need to be mixed into concrete according to the ratio of 2:3:5. Now, according to the needs of building, 2.7 tons of yellow sand is prepared, and how many tons of cement and stones need to be prepared?
Don't use the equation. It seems that we need to add up the 2:3:5 first, and then we don't know how to calculate~
Let cement be x tons of cement: 2 / 3 = x / 2.7 x = 1.8 tons
Suppose that the stone is y ton stone: 3 / 5 = 2.7 / y, y = 4.5 ton
The product is______ The two numbers of are reciprocal______ ．
Two numbers whose product is 1 are reciprocal to each other
RELATED INFORMATIONS
- 1. In a right triangle ABC, the angle c = 90 ° and the side lengths a, B, C satisfy arcsin (1 / a) + arcsin (1 / b) = Pai / 2, and LGC = LGA + LGB
- 2. In the arithmetic sequence an, we know A1 = 3 / 2, d = - 1 / 2, Sn = - 15, find the sum of N and an
- 3. The square of B = AC is ()
- 4. If B ^ 2 = a C = 9, then B is equal to 3 or a 3, there is only one answer
- 5. It is known that the sum of the three positive numbers in the arithmetic sequence is equal to 15, and the three positive numbers are added with 9 in turn, then they are in the arithmetic sequence, and the three positive numbers are solved
- 6. The extremum of higher number. Y = 2x to the third power - 6x square - 18x + 7
- 7. Where is the stationary point of the cubic power of y = 2x - 6x square - 18x + 73 Where 6x square - 12x - 18 comes from? I don't know what derivative is
- 8. If XY satisfies (x-1) ^ 2 + (y + 2) ^ 2 = 4, find the maximum and minimum of S = 2x + y
- 9. If the quadratic function f (x) has f (2 + x) = f (- x) for any real number x, then the equation of symmetry axis of F (x) is?
- 10. F (x) = ax & sup2; + BX (a ≠ 0), if the axis of symmetry of the function is x = 1 and the equation f (x) = x has equal real roots (1) Finding the analytic expression of F (x) (2) If f (x) domain [M, n] and range [2m, 2n], find the value of real number m, n
- 11. It is known that four real numbers - 9, A1, A2 and - 1 are equal difference sequences, and five real numbers - 9, B1, B2, B3 and - 1 are equal proportion sequences, then B2 (a2-a1) = () A. 8B. -8C. ±8D. 98
- 12. If A1, A2, A3 are known to be an arithmetic sequence, B1, B2, B3 are known to be an arithmetic sequence, and these six numbers are all real numbers, then the correct conclusion in the following four conclusions is () ① A1a3 may be established at the same time; ② B1 < B2 and B2 > B3 may hold simultaneously ③ If a1 + A2
- 13. a. The sum of the three numbers is 12, and A-1, B, C + 10 are equal ratio series Big brother, I can guess the numbers
- 14. It is known that a and B are two unequal positive numbers, and a, x, y and B are in equal difference sequence in turn, and a, m, N and B are in equal proportion sequence in turn. Try to compare the size of X + y and M + n
- 15. Isochromatic In the known equal ratio sequence {an}, A3 = 16, common ratio q = 1 / 2 Q: if the sum of the first n terms of the sequence {an} is Sn = 124, find the value of n The first n terms of {an} and Sn = - 2n ^ - n are known Ask: seek a1 + a3 + A5 + +The value of a25
- 16. It is known that a, B and C are equal ratio sequence, B, m, a and B, N and C are two equal difference sequence, then am + CN = () A. 4B. 3C. 2D. 1
- 17. X-8 / 5x = 48 solution equation
- 18. Detailed process of solving equation: 0 = - 1 / 16 (x-4) ^ 2 + 3
- 19. The tangent equation of curve y = 2x + 1 / X at point (1,3) is? Finally, there are steps, The tangent equation of y = 2x + (1 / x) at point (1,3) is
- 20. AB is the diameter of the circle O, C is a moving point on the semicircle, CD ⊥ AB connects Co, CP bisects ∠ OCD, does the position of P change with the position of C?