There are four numbers: 2, - 5,7, - 13. Through what kind of operation, the result is equal to 24?

There are four numbers: 2, - 5,7, - 13. Through what kind of operation, the result is equal to 24?

(2 -7 ×(- 5)) +(- 13)=24

Five people meet to shake hands, two people shake hands, a total of several times

10
C5 2 = 4*5/2 = 10
The first person holds with four people, the second person holds with three people, the third person holds with two people, and the fourth person holds with one person. The total is 10

Simple calculation: 135 △ 12.545: 44 × 37, 27 × 26: 15, 5: 1 × 27 + 5: 3 × 41
1 / 4 × 5 + 1 / 5 × 6 + 1 / 6 × 7 + +39 × 1 / 40

135 ／ 12.5 = 1350 ／ 125 = (1250 + 100) ／ 125 = 1250 ／ 125 + 100 ／ 125 = 10 + 0.8 = 10.845:44 × 37 = 37 × (1-1 / 45) = 37 × 1-37 × 1 / 45 = 37-37 / 45 = 36 + 45 / 45-37 / 45 = 36 + 8 / 4536 and 8 / 4527 × 26:15 = (26 + 1) × (15 / 26) = 26 × 15 / 26 + 1 × 15 / 26 = 15

How to solve the equation of 25% + 4x = 13 / 4

1/4+4x=13/4
4x=13/4-1/4
x=3/4

Simple calculation: 0.11 * 9 * 0.19 + 0.99 * 0.81 and 0.9 / 3.05 * 0.9 * 3.05

0.11*9*0.19+0.99*0.81
=0.99*0.19+0.99*0.81
=0.99*(0.19+0.81)
=0.99*1
=0.99
0.9/3.05*0.9*3.05
About 3.05 points
0.9/3.05*0.9*3.05
=0.9*0.9=0.81

If Sina = 1 / 2, then BC: AC: AB is equal to (1: √ 3:2)
process

Let BC = X
Because ∠ C = 90 degree
So Sina = BC / AB = 1 / 2
So AB = 2BC = 2x
From Pythagorean theorem
AC^2+BC^2=AB^2
So AC = √ 3x
So BC: AC: ab = 1x: √ 3x: 2x = 1: √ 3:2

2005×20062006-2006×20052005=______ ．

2005 × 20062006-2006 × 20052005, = 2005 × 2006 × 10001-2006 × 2005 × 10001, = 0

Circle P and circle O intersect at two points a and B. circle P passes through center O. C is any point on superior arc AB of circle P (not coincident with a and b), connecting AB, AC, OC (1) and
Circle P and circle O intersect at two points a and B. circle P passes through center O. C is any point on superior arc AB of circle P (not coincident with a and b), connecting AB, AC and OC
(1) Point out the angle equal to the angle ACO. (2) when C is at the position of circle P, the line AC is tangent to circle O, reason (3) when the angle ACB = 60 degrees, what is the size relationship between the radii of the two circles

The answer is this:
(1) An angle equal to the angle ACO in the graph is pointed out;
∠ACO=∠BCO
(2) When point C is in circle P, the line CA is tangent to circle O? Explain the reason
When the point is at point D on circle O, the line CA is tangent to circle o
Connect OP and lengthen it. The intersection circle O connects AD and OA at point D
Because C1a is tangent to circle O, so: OA ⊥ c'a
That is, ∠ oad = 90 degree
So when the point is at point D on circle O, the line CA is tangent to circle o
(3) When the angle ACB = 60, what is the relationship between the radius of two circles
Known ∠ ACB = 60 degree
Moreover, from the conclusion of (1), ACO = bc0
Therefore, ACO = bc0 = 30 degree
However, ACO = ADO
So, ADO = 30 degree
In addition, △ ADO is a right triangle
So, do = 2ao
However, do = 2PO
So Po = Ao
So the radii of circle P and circle O are equal

How much is 20 plus 15 plus 32 plus 46.7 plus 58.9 plus 61.2 plus 77.7 plus 88.8?

20 plus 15 plus 32 plus 46.7 plus 58.9 plus 61.2 plus 77.7 plus 88.8

As shown in the figure, AC = AE, ∠ BAF = ∠ bgd = ∠ EAC, is there a triangle congruent with △ Abe in the figure? And prove

In △ ABF and △ DFG, ∠ BAF = ∠ bgd, ∠ BFA = ∠ DFG, ∠ B = ∠ D, ∵ BAF = ∠ EAC, ∵ BAE = ∠ DAC, ∵ AC = AE, ∵ BAE = ∠ DAC, ∠ B = ∠ D, in △ BAE and △ DAC, ∠ B = ∠ D ∠ BAE = ∠ dacae = AC ≌ BAE ≌ DAC (AAS). Answer: Yes. △ BAE ≌ DAC