There is a round flower bed in the park, with a diameter of 30 meters. Grandfather Zhang ran around the flower bed for 5 laps in morning exercise. How many meters did he run this time?

14 × 30 × 5 = 471 meters. A: he ran 471 meters this morning

A square has a circular fountain, the perimeter is 37.68 meters, the area is how many square meters?

3.14 × (37.68 ﹣ 3.14 ﹣ 2) 2 = 3.14 × 62 = 3.14 × 36 = 113.04 square meters. A: its area is 113.04 square meters

The derivative y '= of the function y = x * e to the power X

Y '= the (x-1) power of X * (Ex) multiplied by e means that the x power of ex is the derivative, which is the same as the original formula

The image of the negative x power of function E?

It's a bit like an inverse scale function
You can download a function drawing software on the Internet

Draw the function image f (x) = the second power of negative X - 4x + 5
Mark in the image; opening direction, symmetry axis, Y-axis coordinate, X-axis coordinate, vertex coordinate

From the square of F (x) = - (x + 5) * (x-1) = - (x + 2) + 9, we can see that the parabola is open downward, and its intersection with y = 0 and X axis is (- 5,0), (1,0). The axis of symmetry is x = - 2, its intersection with y is (0,5), and its fixed point is (- 2,9)

How to draw a circle with ruler?
Give you an arc AB, how to determine the center O, draw a circle and make a tangent

Take a point C on arc ab
Connect AC and BC respectively
Do their vertical bisectors separately
The intersection of two vertical bisectors is the center of the circle
Extend the radius so that the extended part is equal to the radius
Make the vertical bisector of the line segment consisting of the radius and the extension. This vertical bisector is the tangent of the circle

How to draw the middle line on the hypotenuse of a right triangle with a ruler

Method:
1. The vertical bisector of the hypotenuse intersects the hypotenuse at M;
2. Connect the right angle vertex C and the point m of the triangle
Then the line cm is the center line on the hypotenuse of the right triangle

How to draw the largest equilateral triangle in a right triangle and prove it

It is known that: RT △ ABC, ∠ C = RT ∠, (1) a & lt; 60 °, 2) a = 60 °, 3) a & gt; 60 °
Find the largest equilateral triangle in RT △ ABC
Methods: (1) 1. Make CD ⊥ AB at point d through point C;
&Nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 2. The midpoint e of CD;
&Nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 3. Take D and E as the center of the circle and de as the radius as the arc, intersecting at point F;
&4. Connect CF and extend AB to point G; 4;
&Nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 5. Intercept DH = DG on ab;
&6. Join ch, then △ CGH is the triangle
&(2) 1. Intercept ad = AC on AB; 2;
&2. Connecting CD, then △ CAD is the triangle
&(3) 1. Take C as the center of the circle, CA as the radius of the arc, and intersect BC at point D;
&2. Take D as the center of the circle, make an arc with the same radius, and intersect with E;
&Nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 3;
&4. Take C as the center of the circle, CF as the radius and make the arc intersection BC at point G, then △ CFG is the triangle

It is ()
A. Know two acute angles B. know a right angle side and an acute angle C. know two right angle sides D. know a right angle side and an oblique side

A. If two acute angles are known to be equal, only two triangles can be obtained to be similar, but two right triangles cannot be judged to be congruent

How to draw an angle exactly the same as the given one by using the rule drawing method
1 for radiation OA
2 take point o as the center of the circle

1. OA of X-ray
2. With o as the center and any length as the radius, draw an arc on OA and intersect OA at point B
3. Keep the radius length of the compass unchanged, take the vertex of the original angle as the center of the circle, cut both sides of the original angle and C, D
4. Take B as the center of the circle, CD as the radius, draw an arc, intersect with the arc just now at point E
5. When OE is connected, EOA is equal to the original angle

There is a round flower bed in the park, with a diameter of 30 meters. Grandfather Zhang ran around the flower bed for 5 laps in morning exercise. How many meters did he run this time?