600 Essays on Circle (1)

The night of Phaeton Siler is beautiful.

The night is like a veil, with charming intoxication, and stars are stuck on it. The beautiful grassland is stained with twilight, and the darkness with dark blue extends far away.

Even though the summer was just over, the temperature at night was still frighteningly low. The campfire has been set up, and the smoke has been dispersed; The fire burned half the sky, and some people had gathered on the stone platform. Gradually, there were more and more people.

The bonfire party kicked off. Everyone orderly formed three circles around the campfire. When the music started, although we didn't know each other, we all sang around the circle hand in hand. "May I hold your hand?" a boy dressed as "Captain America" asked me. I looked down and saw the red light reflected in his watery eyes; I took his hand.

The bonfire burned more vigorously, as if it was ignited by the warm atmosphere. The flame jumped higher and the singing became louder. I felt the sweat on my nose, and the warmth wrapped me tightly. In the dim light, I saw smiling faces flash past my eyes. All of them were smiling from the corners of their eyes, and their cheeks were flushed. Everyone's hands are tightly holding the hands of people around them, whether they know or not.

"Are you happy?" the staff member asked with a microphone, and they all said "happy". "Today is the 70th anniversary of the founding of the Inner Mongolia Autonomous Region. Is there anyone who wants to present a song to everyone?" A lady in a red cotton padded jacket stood in the middle of the circle and sang a familiar folk song, with a melodious voice; Everyone hummed along with his singing. When the song was over, the applause was thunderous; The lady smiled and handed the microphone to the next person. More and more people are singing on the stage. "Have a good time!" A man rushed to the stage and spoke loudly with the microphone. He had beer in his left hand and his face was red; There was a big smile at the bottom, and everyone's face was suffused with red light of joy.

I quietly quit the stream of people; The cold came again. The air was fragrant with soil and grass, and there was a smell of ignition. The night sky is low, as if you can pick stars.

I walked to my yurt. Here, beside us, either Han or Mongolian, or relatives, or friends, or even strangers who have never met before, the blood of the Chinese nation connects us closely and draws a big concentric circle.

Late at night, the distant campfire is still jumping.

600 Essays on Circle (2)

In the campus, there is a circle, that is the school playground. It is oval, with green grass in the middle of the red plastic runway, which is very eye-catching. That circle records every bit of my growth.

My relationship with the playground began in the first grade. One day, I was playing with my classmates on the playground. Suddenly, I tripped over a bump on the ground and fell on my face. The red blood on the knee immediately flowed out. That injury kept me confined in my seat for a whole week. The pain in my heart made me afraid of the playground.

After that, I walked to the corner of the playground, where I was once bleeding and injured, and I was always cautious. Until the third grade, I finally got rid of the psychological shadow, but the fearsome 800 meters followed. Running on the red plastic ground, I was breathless, especially in the last few laps, my legs seemed to be filled with lead, and I was completely mechanically circling on the playground runway. The eyes began to become a little fuzzy, and the throat became more and more dry... Finally, I insisted on the end, I felt as if it had been a century. I lay panting on the lawn, not wanting to look at the red circle again.

It was not until the sixth grade that I realized that my free running time on the red playground was getting shorter and shorter. This red circle records my laughter! In the hot summer, my friends and I took a thermometer to find a cool place on campus. In autumn, the heat hasn't faded yet, and drops of sweat sprinkle on the basketball court, making the ground bright. What was left on the playground were wonderful shots and excited shouts. Occasionally, a snow fell quietly. We put on a rare thick snow quilt on the playground. We put on a heavy coat and played a snowball fight here, leaving us laughing in the snow. Soon it was spring again, the vegetation began to sprout, and the peach and cherry blossoms next to the playground opened again

I squatted down and touched the playground in the sunset. The evening breeze brings the fragrance of green grass. Deep in my heart, I seem to hear the sound of running

600 Essays on Circle (3)

In the original, the compass was not invented, so how did the ancient people draw a circle? In class, we suspect that people may have used several methods: first, the thumb of one hand is fixed, the middle finger is stretched to the maximum, and it rotates around the thumb. But this method cannot guarantee whether the thumb position is moved, which is obviously not feasible; Second, draw a circle around the bottom of the cup. This method can ensure the accuracy of the circle, but it is not perfect because it cannot change the size; Third, open an arm, stick it to the blackboard, and swing it to draw a big circle. This method is more impractical. The circle is too big, and even the blackboard has no place for it; Fourth, find a shoelace or thin line, tie a pencil on one end, fix the other end with your hand, straighten the line, rotate the pencil around the other end, and draw a perfect circle. This method simulates the compass to the maximum extent, which can control the size and is very accurate.

Now, compasses are very common. It is also very important to learn how to use the compass: first, use your right hand to pick up the handle of the compass, divide the two feet to the specified radius distance, then tie the pointed foot on the center of the circle (can't move), rotate it with force, and finally, mark the center, radius and diameter of the circle as required.

So what about the concept of circle? We think there should be the following points: 1. Center (O): the point where the sharp foot is when drawing with a compass. The center of the circle determines the position of the circle. 2. Radius (r): there are countless line segments connecting the center of the circle and any point on the circle. The radius determines the size of the circle. 3. Diameter (d): there are countless line segments passing through the center of the circle and having two ends on the circle. 4. In a congruent circle or equicircle, all radii are equal and all diameters are equal. 5 The diameter length is twice the radius: 2r=d; The radius length is?? of the diameter?;? d=r。6、 A circle is an axisymmetric figure, and the line where the diameter lies is the symmetry axis of the circle. A circle has countless axes of symmetry. As for the circumference of a circle, there are the following points: 1 Pi: the ratio of the circumference to the diameter of a circle. It is an infinite acyclic decimal, π......, which is usually taken as π in practical applications. Formula: C=π d=2 π r.