It is known that the length of rectangular ABCD is 30cm and the width is 20cm. A proper plane rectangular coordinate system is established, and the coordinates of a, B, C and D are obtained first Then the rectangle is made in the rectangular coordinate system ABCD.Thank you

It is known that the length of rectangular ABCD is 30cm and the width is 20cm. A proper plane rectangular coordinate system is established, and the coordinates of a, B, C and D are obtained first Then the rectangle is made in the rectangular coordinate system ABCD.Thank you

A - 15 10 B15 10 C15 - 10 d - 15 - 10 this is the coordinate with the center of the rectangle as the origin

The diameter of the bottom surface of a cylindrical pool is 8 meters and the depth of the pool is 3 meters. If tiles are pasted on the bottom and around the pool, the area of each tile is 2 square decimeters,
How many tiles do you need at least?

Bottom radius = 8 △ 2 = 4m
Total area of pool bottom and surrounding area = 3.14 × 4 & # 178; + 3.14 × 8 × 3 = 125.6m2 = 12560m2
So it needs at least 12560 △ 2 = 6280 pieces