The area of an isosceles triangle is 8 square decimeters, and eight such triangles form a square. Its area is () square decimeters, and its perimeter is () decimeters

The area of an isosceles triangle is 8 square decimeters, and eight such triangles form a square. Its area is () square decimeters, and its perimeter is () decimeters

The area of an isosceles triangle is 8 square decimeters, and eight such triangles form a square. Its area is (64) square decimeters, and its perimeter is (32) decimeters

The isosceles triangle has the largest area among all the triangles whose perimeter is fixed. How to prove it?
Such as the title

A + B + C = 2p (P is constant)
According to Helen's formula:
S^2=p(p-a)(p-b)(p-c)
=3(p/3)(p-a)(p-b)(p-c)

On every digit_____ The number corresponding to this digit_______ The product of multiplication is the size of the bit value

Value, weight

Write the formula and formula
1. As shown in the picture, Xiao Ming rolls an iron ring on the same road. The diameter of the iron ring is 30 cm, and it rolls 47.1 cm. How many times has the iron ring rolled?
2. As shown in the figure, the circumference of the circular pool is 78.5m. What is its diameter? What is its radius? (accurate to 0.1M)
3. Using a 20cm thin steel wire as material, three circular steel rings of the same size (excluding the loss at the joint) are made. As a result, there is 1016cm long steel wire left. What is the diameter of the circular steel ring?

(1) Girth of iron ring = π d = 3.14 * 30 = 94.2 cm, 47.1 / 94.2 = 0.5, half circle
(2) D = C / π = 78.5 / 3.14 = 25cm, r = D / 2 = 12.5cm
(3) 20-1.16 = 18.84cm, each ring consumes 18.84g3 = 6.28cm
D = C / 2 = 6.28 / 3.14 = 2cm

How to use 1.2.3.4.5 to make the result equal to 999

5 to the third power, multiply by 4, multiply by 2, minus 1

3.6 times 10 x power = 0.36 x = detailed process

∵3.6×0.1=0.36
∴10^X=0.1
X=-1.

1, sequence: 1 + 3 + 5 + +（2n+1)=
2. Given the complex z = cost = isint (- 1 is less than t is less than 0), which quadrant is the corresponding point of complex Z?
How about the number of items in the first question?
Question 2: given the complex z = cost + isint (- 1 less than t less than 0), which quadrant of the complex plane is the corresponding point of the complex Z?

1.
Because 1 = 2 * 1-1
3=2*2-1
5=2*3-1
2n+1=2（n+1）-1
So there are n + 1 terms
1+3=2^2
1+3+5=3^2
……
Original formula = (n + 1) ^ 2
two
cost>0 sint

What is the distance from point to point? What is the distance from point to line?
On parallelogram

The distance from point to point is the length of line segment between two points, and the distance from point to line is the length of vertical line segment

It is known that a > O.B > O.C > O and a + B + C = 1. It is proved that the square of a + the square of B + the square of C is equal to one third

(a + B + C) & sup2; = 1 (a + B + C) & sup2; = A & sup2; + B & sup2; + C & sup2; + 2Ab + 2BC + 2aca & sup2; + B & sup2; + C & sup2; ≥ AB + AC + BCA & sup2; + B & sup2; + C & sup2; + 2 (A & sup2; + B & sup2; + C & sup2;) ≥ 1, so a & sup2; + B & sup2; + C & sup2; ≥ 1 / 3

Derivative dy / DX of implicit function y = y (x) determined by equation 2Y = x + LNY

d2y=d(x+lny)
2dy=dx+dlny
2dy=dx+dy/y
So dy / DX = 1 / (2-1 / y) = Y / (2y-1)