Now, a rectangle with a length of 4cm and a width of 3cm is rotated around the straight line of its length and width respectively to get different cylinders. How big are their volumes?

Now, a rectangle with a length of 4cm and a width of 3cm is rotated around the straight line of its length and width respectively to get different cylinders. How big are their volumes?

The volume of the cylinder is: π × 32 × 4 = 36 π cm3 when it rotates around the straight line where the length is located. The volume of the cylinder is: π × 42 × 3 = 48 π cm3 when it rotates around the straight line where the width is located

A rectangle with a length of 4cm and a width of 3cm rotates around its length and width respectively to get different cylinders with different volumes

Around the long side: 9 * faction * 4 = 36 faction
Short side: 16 * 3 * faction = 48 faction

There is a rectangle with a length of 4cm and a width of 3cm. We rotate it around the straight line of its length to get the volume of the cylinder?
It's 48 paicm, but I don't know why it's 4 * 4 * Pai * 3

If you have a book in your hand, stand on the table (or in the air) and rotate according to the long side
So what you get is a circle swept by the short side and a cylinder swept by the long side
The volume calculation is 3 * 3 * Pai * 4, that is, the area of the bottom circle (the radius is the short side) multiplied by the height (the long side) is 36pai square centimeter
If you rotate it by the short side, you will get 48 paicm square
The truth is the same