Have you ever gone shopping? Have you ever shared anything with your partner? At this time, you have unconsciously used the knowledge of mathematics.
In fact, mathematics comes from life, serves life and is applied everywhere in life.
As middle school students, although the knowledge we have can't solve the problems of spaceship going to the sky and the design of Olympic venues, we can also solve some complicated practical problems in our lives.
Just like the other day, math knowledge helped me a lot!
My birthday is coming. If you want to make your own birthday hat at the birthday party, just do it. I bought colored paper in a hurry, drew it into a fan shape, and then cut it out ... once or twice, it was all done. I wore my new birthday hat on my head, which was really shocking. My birthday hat covers my face. So I made another one, thinking: I made it too big just now, and now if I make it smaller, there will be no problem! However, contrary to expectations, this time it is too small. It is really furious. Too big at once, too small at once. What the hell! Just when I was furious and couldn't get my birthday hat, a phone call reminded me.
It turned out that my classmates asked me how to do my math homework. So my mind flashed: haven't we just learned cones these days? Oh, I am so confused! If there is a shortcut, don't take a detour and ask for trouble.
So, I took action.
First of all, calm down and outline the shape and structure of the birthday hat in your mind.
Then draw the approximate image of the hat after it is unfolded: it is a fan, the radius is the generatrix length of the cone, and the arc length is the circumference of the bottom of the cone-the size of the hat mouth. Therefore, we must first measure the size of our head and determine the size of the cap. According to the formula of pi c=2πR, we can know the radius r of the cone bottom (the radius of the hat mouth) and how high the hat should be first.
After thinking clearly in my mind, I started the specific implementation work: I measured 5 7cm with a tape measure in the first week, and the height of the hat to be made was 28.5cm.
Then the calculation is as follows
∫c = 2πR, that is, 57 = 2× π r.
∴r≈9 cm；
∫L2 = H2+R2
∴l=30cm；
The arc length of the sector, that is, the circumference of the bottom surface, is 2πR =nπl/ 180.
∴ Central angle n = 57×180/15 π ≈109.
After the calculation, prepare the paper, draw a sector according to the calculated size (leaving a rubbing seam), then cut out the sector with scissors, and finally rub the two radii of the sector together with double-sided tape, so that a birthday hat is finished. There is mathematics everywhere in life. As long as we learn theoretical knowledge well and learn to use it, we can solve many mathematical problems in life. If theory is to be combined with practice, mathematical knowledge can no longer just think and do problems, but can serve the needs of our lives.