The ratio of () to () of a circle is called PI, which is represented by the letter ()

The ratio of () to () of a circle is called PI, which is represented by the letter ()

Circumference diameter π

PI is the ratio of (?) and (?), which is expressed by the letter (?)

PI is the ratio of (circumference) to (diameter), expressed by the letter (π)

In large and small circles, their circumference is always more than three times the diameter of their respective circles. We call this fixed number (PI), using the letter (π) It is a (infinite non cyclic decimal) between () and (). In calculation, only its approximate value () is taken

It is a (infinite non cyclic decimal) between (3.1415926) and (3.1415927). In calculation, only its approximate value (3.14) is taken

PI is the ratio of circumference to diameter, so circumference is the product of diameter and PI, right

PI is the ratio of circumference to diameter, so circumference is the product of diameter and PI

The ratio of the diameter to the circumference of a circle is called the ratio of circumference Is it right or wrong

wrong.
What is right is:
The ratio of ratio to circumference is called circumference

PI is the ratio of circumference to diameter

Right

Each angle of the hexagon ABCDEF is 120 degrees, and AF / / CD, EF / / BC, Fe = AF = 8, ab = 2, de = 3, can you determine the circumference Tell me how to add auxiliary lines

Because the angle Fab = angle CBA = 120 ° so the angle PAB = angle PBA = 60 ° obviously △ PAB is an equilateral triangle. Similarly, the other adjacent angles C, angle D; the angle F, angle e are all filled into an equilateral triangle △ CQD △ ERF because the triangles P, Q and R are all 60 ° (because they are all equilateral △), the large triangle PQR is also equilateral

Given the hexagon ABCDEF, his inner angle is 120 degrees, AF = EF = 3, ab = 1, ed = 2, find the circumference

Fifteen

Given the circle C1: x2 + Y2 + 6x-4 = 0 and circle C2: x2 + Y2 + 6y-28 = 0 (1), the linear equation passing through the point (2,1) and perpendicular to the common chord of circle C1 and circle C2 is known (2) Find the common chord length of circle C1 and circle C2

1、
Subtracting two circles
The common chord is 6x-6y + 24 = 0
The slope is 1
So vertical k = - 1
So Y-1 = - (X-2)
x+y-3=0
2、
(x+3)²+y²=13
Center C1 (- 3,0) r = √ 13
The string is 6x-6y + 24 = 0
That is, X-Y + 4 = 0
Then the chord center distance is d = | - 3-0 + 4 | / √ (1? 2 + 1?) = 1 / √ 2
So the chord length = 2 √ (r? - D?) = 5 √ 2

Circle C1: x2 + y2-6x-6 = 0 circle C2: x2 + y2-4y-6 = 0 The equation of common string is obtained

C1：(x-3)²+y²=15
C2：x²+(y-2)²=10
It is easy to obtain, the center distance d = √ 13, R1-R2 = √ 15 - √ 10, R1 + R2 = √ 15 + √ 10
r1-r2