The radius ratio of the two gardens is 2:1. The area of one circle is 36 square cm, and the area of the second circle is 36 square cm

The radius ratio of the two gardens is 2:1. The area of one circle is 36 square cm, and the area of the second circle is 36 square cm

144 or 9

The relationship between the area s (square of CM) and radius R (CM) of a circle is s = the second power of π R. now we want to make a circular part with the area of 49 π cm to the second power. What is the radius of this part?

r²=49∏÷∏=49
R = 7 (- 7 rounding off)
That is: the radius of this part is 7cm

If the radius of a circle is increased by 1 / 5, its area will be increased by 88 square decimeters
I'm going to hand it in soon. It must be the first grade of junior high school. Many people in Baidu have asked this question, but I can't understand it. I can understand it in any way

Make an equation: the area of the later circle minus the original area is 88
π(r+1/5r)² — πr² = 88
We obtain 11 / 25 π R & # 178; = 88
πr² =200
So the original area is 200 square decimeters