There is a round flower bed with a circumference of 37.68 meters. A 1-meter path is paved around the flower bed. What is the area of the path?

There is a round flower bed with a circumference of 37.68 meters. A 1-meter path is paved around the flower bed. What is the area of the path?

1. According to the perimeter, the flower bed radius is 37.68/3.14/2 = 6
2. The area of flower bed S1 = 3.14 * 6 * 6 = 113.04
3. Radius plus one meter, the common area of flower bed and path is S2 = 3.14 * 7 * 7 = 153.86
4. The common area minus the area of flower bed is the area of path s = s2-s1 = 153.86-113.04 = 40.82

Is the predicate verb of a box of apples singular or plural
the sooner the better

We can't simply say what form it is
In general, we prefer the principle of proximity, but we usually do odd numbers
ex.There is a box of apples.
The box of apples are all red.

In the triangle ABC, the edges corresponding to the angle ABC are ABC, C = 3 / 4 π, Sina = root 5 / 5.1; find the value of cosa and SINB
c'mon

COS²A+SIN²A=1
COS²A=20/25
Because C = 3 π / 4, it is an obtuse triangle
COSA=2√5/5
SINB=SIN（π-A-C）
=SIN（A+C）
=SINACOSC+COSASINC
=√5/5×（-√2/2）+2√5/5×√2/2
=√10/10

The past tense of English irregular verbs
I need the past tense of all the irregular verbs before the third day of junior high school
Example: See Saw

1. Remove E in the middle and add t at the end, such as: keep → keep, feel → feel, sleep → sleep, sleep → sweet
2. The ending d changes to t, such as: build → build, lend → lent, send → send, spend → spent
3. Change "I" to "a", such as "ring → rang, sit → sat, drink → sink, sing → sang, swim → swim, begin → begin, give → gave"
4. "Riding", "driving", "writing" - change I into o, such as ride → ride, drive → drop, write → write
5. Think, buy, bring and fight
6. "Teaching" and "grasping" -- never forget aught, such as: teach → taught, carry → caught
7. Changing "ow / AW" to "Ew" is a new fashion, such as "know → know, grow → grew, throw → threw, draw → draw"
8. The past tense of "put", "let" and "read" is the same as the original, such as: put → put, let → let, read → read / red

Archimedes said that giving me a fulcrum can pry up an earth. What's the principle? Is that reasonable? What's the principle of leverage

It is reasonable that this is the principle of lever. Power × power arm = resistance × resistance arm is expressed by algebraic formula F1 & ﹥ 8226; L1 = F2 & ﹥ 8226; L2. In the formula, F1 represents power, L1 represents power arm, F2 represents resistance, L2 represents resistance arm. It can be seen from the above formula that in order to achieve balance of lever, power arm is several times of resistance arm, and power is a fraction of resistance
Archimedes said is the labor-saving lever, namely L1 > L2, F1

How to calculate the voltage Uc at both ends of capacitor in sine RC series circuit?
The resistance R is 150k, the capacitance is 47uF, UI = 220 V, f = 50 Hz

Uc=ui*（1/jwC）/(R+1/jwC)=ui/(jwRC+1)
Where j is an imaginary unit, it can also be regarded as a phase angle of 90 degrees;
Angular frequency w = 2 * pi * F, R is resistance, C is capacitance
The answer must be vector, with modulus and angle

What is multiplier? What are the preconditions for multiplier to play a role in economy?

The ratio between the change in income and the initial change in expenditure that brings about this change is expressed as k = YGJ, where y represents the change in national income and j represents the change in expenditure. For example, if k = 2, then the annual expenditure flow, such as investment, continues to increase, Conditions: first, there are underutilized resources in the economy. In this way, the increase of total demand will increase the national income. Otherwise, the increase of national income will be limited by the resource conditions, and the total demand will not stimulate the economy, Sometimes most of the resources in the economy are not fully utilized, but because one or several important resources are in a "bottleneck state", the multiplier will also be limited to play its role. The "bottleneck state" of this kind of resources makes it impossible to use other idle resources. Secondly, it is necessary to assume that investment and storage are independent of each other, Third, the increase of money supply should be able to meet the needs of increasing expenditure, When investment and consumption increase, the increased money demand will not be supported by money supply, which will lead to the rise of interest rate and inhibit consumption and investment

How to read giraffe

Giraffe plural: giraffes, giraffe [example] how do you put a giraffe into a refrigerator

In the parallelogram oabp, the line passing through the point P intersects the line segments OA and ob at the points m and N respectively, if the vector om = x, the vector OA, the vector on = y, the vector ob, (0

1. OP = AB = ob - OA, then nm = om - on = x OA - y ob, MP = op - om = (ob - OA) - x OA = - (1 + x) OA + OB and nm ‖ MP, X-Y (1 + x) = 0, that is, the analytic expression of the function is: F (x) = x x x + 1 (0 < x < 1); 2

How many percent more is the smallest sum than the smallest prime?

（4-2）÷2×100%=100%
Analysis: the minimum composite number is 4, and the minimum prime number is 2