The perimeter of a rectangle is 8 more than that of a circle. Calculate the perimeter of a rectangle, the perimeter of a circle, the area of a rectangle and the area of a circle

The perimeter of a rectangle is 8 more than that of a circle. Calculate the perimeter of a rectangle, the perimeter of a circle, the area of a rectangle and the area of a circle

The premise of conjecture is: circle inscribed and square long two sides
Give a solution to the problem
Suppose the two sides of a rectangle are a, B, and a

Square and circle of equal circumference______ It has a large area

Among all figures with equal perimeter, the circle has the largest area

Is the circumference of a circle greater than that of a square when the areas are equal

The area of the circle = π R ^ 2, the area of the square = a ^ 2
The circumference of a circle is 2 π R, and that of a square is 4a
If the area is equal, π R ^ 2 = a ^ 2, then a = R √π
Circle perimeter = 2 π r square perimeter 4A = 4R √π
Comparing the two sizes, we can see that a square is bigger than a circle. The above two formulas are not the same. They can be bigger than their square

Which area is larger for a square or circle with equal perimeter? (c means perimeter)

Let X be the circumference, a be the side length of a square, B be the length and C be the width of a rectangle, and R be the radius of a circle
Then the side length of the square is a = x / 4
Square area s Square = a * a = x ^ 2 / 16
If the circumference of a circle is x = 2 π R, then r = x / 2 π
Area of circle s circle = π R ^ 2 = x ^ 2 / 4 π
Rectangle perimeter x = 2B + 2C (c + b) = x / 2
Rectangle area s rectangle = b * C
Square area X ^ 2 / 16, circle area X ^ 2 / 4 π,
First compare the area of a square and a circle
Obviously, the denominator 16 in x ^ 2 / 16 is larger than the denominator 4 π in x ^ 2 / 4 π, and the number with the same numerator and larger denominator is smaller
So x ^ 2 / 16 is less than x ^ 2 / 4 π, so the square area is less than the circle area
S circle > s Square

(1 / 7-1 / 9) × 6.3 + 2 / 5 simple calculation helps

（1/7-1/9）x6.3+2/5=1/7x6.3-1/9x6.3+0.4=0.9-0.7+0.4=0.6

Simple calculation of 2.54 + 9.16-9.16 + 9.46

2.54+9.16-9.16+9.46
=(2.54+9.46)+(9.16-9.16)
=12+0
=12

16.46 * 15.3 + 8.54 * 15.3-25 * 14.9 (simple calculation)

=(16.46+8.54)*15.3-25*14.9
=25*15.3-25*14.9
=25*(15.3-14.9)
=25*0.4
=10

How to calculate 2.54-8.16 + 9.46 + 9.16? Urgent

=（2.54+9.46）+（9.16-8.16）
=12+1
=13
If you are satisfied with my answer, please continue to ask until you understand!

1.1+1.3+1.5+1.7+…… +7.9 how to calculate simply

This is obviously the summation problem of arithmetic sequence, the first term is A1 = 1.1, the tolerance is d = 1.3-1.1 = 0.2, then an = a1 + (n-1) d = 0.2N + 0.9, so an = 7.9, then 0.2N + 0.9 = 7.9, so n = 35, so there are 35 terms in total, so 1.1 + 1.3 + 1.5 + 1.7 + +7.9=S35=35(a1+a35)/2=35*(1.1+7.9)/2=157.5...

Simple operation: 7 / 9 + 1 / 7 + 2 / 7 + 1 / 3

7/9+1/3=10/9=1+1/9
1/7+2/7=3/7
3/7+1/9=34/63
So the final result is 1 + 34 / 63 = 1 and 34 / 63