A formula for finding the circumference of a semicircle

A formula for finding the circumference of a semicircle

Circumference of semicircle = half circumference of circle + diameter = π D △ 2 + D = π R + 2R = (π + 2) r
π R + 2R or π R + D remarks: D = diameter, r = radius
PI R
πr+2r
Because the circumference of a circle is equal to 2 π R, then the circumference of a semicircle is π R
What is the formula for the circumference of a semicircle?
2r*(Pi/2)+2r
R is the radius of the semicircle and PI is the circumference
It's half of the circumference of a circle plus the diameter. I don't know the formula of the circumference of a circle
Say the formula for calculating the circumference and area of a circle
The letter expression of the circle perimeter calculation formula is: C = π D or C = 2 π R, and the letter expression of the circle area calculation formula is: S = π R2
On the position relationship between circles
If the tangents of two circles x ^ 2 + y ^ 2 + 4Y = 0, x ^ 2 + y ^ 2 + 2 (A-1) x + 2Y + A ^ 2 = 0 at the intersection are perpendicular to each other, then the value of real number a is__________ .
Simplify the second circle: [x - (A-1)] ^ 2 + (y + 1) ^ 2 = 2-2a, ∵ 2-2a > 0, ∵ a < 1, ∵ the tangents of the two circles at the intersection are perpendicular to each other, ∵ the tangents of any circle must pass through the center of the other circle, ∵ the radii of the two circles and the connecting lines of the two circles form a right angle trigonal
4 + (2-2a) = [(A-1) - 0] ^ 2 + [- 1 - (- 2)] ^ 2, the reduction is: 6-2a = (A-1) ^ 2 + 1, that is: A ^ 2 = 4, a = 2 or - 2, ∵ a < 1, ∵ a = - 2
On the positional relationship between circles
If the circle O1 and O2 with radius R1 and R2 share a common chord AB, and ab is equal to 2a, then the connecting centerline O1O2 =?
Shouldn't intersection be divided into big intersection and small intersection? The answer is only one. How many answers are there?
There are two positive answers
Intersection should be divided into big intersection and small intersection. There should not be two answers to this question. It is wrong to write only one answer
r1-r2
The problem of circle and its positional relation
In the two concentric circles with o as the center, the radius of the big circle R is 9, and the radius of the small circle R is 3. Find the radius r 'of the circle where the big circle and the small circle are tangent
Because the diameter of the concentric tangent circle must be R-R = 6, the radius is 3
Three
6 or 3
The positional relationship between circles
Known circle C: x ^ 2 + y ^ 2-2mx + 4Y + m ^ 2-5 = 0
Circle C ': x ^ 2 + y ^ 2 + 2x-2my + m ^ 2-3 = 0
When m is a number, two circles are circumscribed, circumscribed, intersected, inscribed and included?
Circle C: x ^ 2 + y ^ 2-2mx + 4Y + m ^ 2-5 = 0 and circle C ': x ^ 2 + y ^ 2 + 2x-2my + m ^ 2-3 = 0 x ^ 2 + y ^ 2 - 2mx + 4Y + m ^ 2 - 5 = x ^ 2 - 2mx + m ^ 2 + y ^ 2 + 4Y + 4 - 9 = (x-m) ^ 2 + (y + 2) ^ 2 - 9, x ^ 2 + y ^ 2 + 2x - 2My + m ^ 2 - 3 = x ^ 2 + 2x + 1 + y ^
X^2+Y^2-2MX+4Y+M^2-5=0
The standard equation of rounding
(x-m)^2+(y+2)^2=3^2
X^2+Y^2+2X-2MY+M^2-3=0
The standard equation of rounding
(x+1)^2+(y-m)^2=2^2
It can be seen that the two circles are
A circle with (m, - 2) as the center and 3 as the radius
A circle with (- 1, m) as its center and 2 as its radius
Want two circles circumscribed? Then the center of the circle... Unfolds
X^2+Y^2-2MX+4Y+M^2-5=0
The standard equation of rounding
(x-m)^2+(y+2)^2=3^2
X^2+Y^2+2X-2MY+M^2-3=0
The standard equation of rounding
(x+1)^2+(y-m)^2=2^2
It can be seen that the two circles are
A circle with (m, - 2) as the center and 3 as the radius
A circle with (- 1, m) as its center and 2 as its radius
Want two circles circumscribed? Then the sum of the distances between the center of the circle is the sum of the radii
Then (M + 1) ^ 2 + (- 2-m) ^ 2 = 5 ^ 2
There are 2m ^ 2 + 6m-20 = 0
m^2+3m-10=0
The solution is m = 2, M = - 5
How far away? The distance between the center of the circle is required to be greater than the sum of the radii
That is, (M + 1) ^ 2 + (- 2-m) ^ 2 > 5 ^ 2
The solution is m > 2 m
The positional relationship between point and circle the positional relationship between circle and circle
Chapter 3 the relationship between line and circle, the relationship between circle and circle
2. Fill in the blanks (3 points per question, 18 points in total) 11. - 2 12. Not unique, such as 13. 4 14. 15cm 15. 16. ② ③ 3. Answer questions (46
A third day mathematics problem (circle and circle position relationship) urgent!
As shown in the figure (I can't draw with my mobile phone) circle O1 and circle O2 intersect at the center of a and B. on circle O2, the diameter of circle O2 AC intersects circle O1 at the extension line of point DCB intersects circle O1 at E. note: (1) AE is the diameter of circle O1 (2) ad = be. Please answer quickly. Thank you
Proof: (1) make auxiliary line: connect ab
Because AC is the diameter, the angle ABC is a right angle
Because EBC is a straight line, the angle Abe is a right angle;
So AE passes through the center, that is, AE is the diameter of circle O1
(2) Make auxiliary line and connect BD
On the circle O1, there is Pythagorean theorem
AB*AB+BE*BE=AE*AE
AB*AB+AD*AD=AE*AE
So ad * ad = be * be
That is, ad = be