Who will do these math problems. The third year of junior high school

According to the problem, it is known that the CD line segment is 1, the diameter of the circle is 2, and the three points of CDE are moving, so the minimum time of DE is when D is perpendicular to AP.

When point C coincides with point B, the value of BC+DE is the smallest.

So the minimum value is bc+de=0+.

The answer is that this question is a fill-in-the-blank question at first glance, and it is very important to control the time of fill-in-the-blank questions, this kind of question generally has skills, I do this: first move point c to point b, at this time the length of bc is 0, so only the minimum value of de is required, ap and ab are perpendicular to each other, e is the moving point on ap, d is the point on the semicircular arc, cd=1, and the radius of the circle is also 1, so the triangle ocd is an equilateral triangle, which coincides, and at this time connect de, only de ab, de is the smallest, Make a high line from point D to the oc side of the triangle ocd, so that the intersection point is m, and because the three lines of the equilateral triangle are one, so om=,de=ao+om=, so bc+de=;

At the other extreme, point D coincides with point A. At this time, a, d, e three points coincide to get de=0, at this time bc and cd and ab form a right triangle, and ab=2, cd=1, so bc is the root number 3, because it is greater than, so the minimum value of bc+de is taken.

To solve it with congruent triangles, the answer is 3 2

1) From the image, it can be seen that the company began to turn a profit after the end of the fourth month.

2) From the image, we can see that the vertex coordinates are (2,-2), so we can set the function relationship as: y=a(t-2)2-2

The graph of the relationship of the function is obtained by (0,0).

a(t-2)2-2=0, the solution is a= .、

The function relationship is s=t-2)2-2 or s=t2-2t

3) Substitute s=30 into s=t-2)2-2 to get t-2)2-2=30

The solution yields t1=10, t2=-6 (rounded).

Answer: As of the end of October, the company's cumulative profit can reach 300,000 yuan.

4) Substituting t=7 into the relation, we get s=72-2 7=.

Substituting t=8 into the relation, we get s= 82-2 8=16Answer: The company's profit in the 8th month is 10,000 yuan. Oh.

Where's the picture? I can't see.

For the time being, it seems that this can only be done by finding a regular method. By solving the equations, we can find the a1 ordinate 3, the a2 ordinate-3 (2-1), and the a3 ordinate 3 (3-2)

It can be seen that the general formula of the an ordinate is .

1)＾n×√3( √n - n-1) )

Solution: Let the growth rate be x

4(1+x)²=

1+x）²=

1+x= x= or x= rounded off negative values).

So the growth rate is 10%.

With a similar shape, a triangle with area 2 is the same height as a triangle with area 3, and the ratio of the base is 2:3, so the area ratio of the triangle with area 2 and the large triangle below is 4:9, so the area of the large triangle below is 9 2, and the area of 9 2+3-2 is the shadow area.

Let the length of the rectangle be a, the width be b, and the area of the large triangle formed by the combination of two small triangles marked with area = 1 2 * (1 2a) b = 5, then the area of the rectangle ab = 20.

Half = 10, shaded area = 10-2 = 8

No, search for it on the Internet, there should be.

Extend the AD to BC at point E.

ab=ACAE bisects BC vertically (a point at an equal distance from the two endpoints of a line segment, on the perpendicular bisector of that line segment).

AE Vertical BC

and ab=ac, ae perpendicular bc

AE bisects BAC (three-in-one) is AD bisecting BAC

Champion 365 "Teacher answers: rectangle, parallelogram, diamond.

All are parallelograms. It has a relationship with the diagonal. The diagonal is perpendicular to the diamond. The diagonal is equal to the rectangle. Not perpendicular and not equal to the diamond.

The midpoint of connecting the sides of the diamond gives a rectangle, the parallelogram gives a parallelogram, the rectangle gets a diamond, the line segment of the new figure must be related to the diagonal, the four sides are parallel to the opposite diagonal, and the four corners are equal to the angles of the opposite diagonal.

1.Connecting the midpoints of the diamond gives you a square.

Because the diagonals of the diamond are perpendicular to each other. According to the nature of the median line, the adjacent sides of the quadrilateral are perpendicular to each other.

According to the fact that the four sides of the diamond are equal, the adjacent sides of the resulting quadrilateral are equal. So it's square.

2.Connecting the midpoints of the parallelogram gives you the parallelogram. (nature of the median line)3Connecting the midpoints of the rectangle gives you a diamond.

Because the connection is obtained according to the nature of the median line, this figure is a parallelogram.

The four sides are equal. According to the Pythagorean theorem or congruent triangles, it can be known.

The diagonal of this graph is the two median lines of the rectangle, which are perpendicular to each other.

So this quadrilateral is a diamond.

Connecting the midpoint of the diamond gives you a rectangle.

Connecting the midpoints of the flat quadrilateral gives you a flat quadrilateral.

Connecting the midpoints of the rectangle gives you a diamond.

The shape of a new figure obtained by connecting the midpoints of each side of a quadrilateral in turn is related to the diagonal: the length of the new side = the length of the original diagonal 2

The midpoint of the diamond gives a rectangle.

The midpoint of the parallelogram gives the parallelogram.

The midpoint of the rectangle gives the diamond.

It has to do with the diagonal.

The line connecting the midpoints of each side of the quadrilateral must be a parallelogram, and the length of the two pairs of opposite sides is half the length of the two diagonals of the original quadrilateral.

Rectangles, parallelograms, rhombuses.

All are parallelograms. It has a relationship with the diagonal. The diagonal is perpendicular to the diamond. The diagonal is equal to the rectangle. Not perpendicular and not equal to the diamond.

The midpoint of connecting the sides of the diamond gives a rectangle, the parallelogram gives a parallelogram, the rectangle gets a diamond, the line segment of the new figure must be related to the diagonal, the four sides are parallel to the opposite diagonal, and the four corners are equal to the angles of the opposite diagonal.

Using the definition of congruence, and the median line theorem, the characteristics of the edges of each graph, look at the relationship and angle of the four.