Joke Collection Website - News headlines - There are three kinds of punctuation marks on the school placard (the colored part in the picture). The radius of the big circle is known as r, and the radius of the small circle is known.

There are three kinds of punctuation marks on the school placard (the colored part in the picture). The radius of the big circle is known as r, and the radius of the small circle is known.

1. Circle: S=π(R? -r？ )=3πr？

Second, Tai Chi: This can be seen directly. The area of black and white is half: S=0.5*πR? =2πr？

3. Add a small circle at three quarters of the ring: S=(3/4)*3πr? +πr？ =( 1 1/4)πr？

Obviously, the smallest area is the second Tai Chi pattern.

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