Around a round pool with a diameter of 10 meters, build a stone road with a width of 1 meter. What is the area of this stone road?

Around a round pool with a diameter of 10 meters, build a stone road with a width of 1 meter. What is the area of this stone road?

10 △ 2 = 5 (m) 5 + 1 = 6 (m) 3.14 × (62-52) = 3.14 × (36-25) = 3.14 × 11 = 34.54 (M2). A: the area of this stone road is 34.54 m2

The speed ratio of a and B is known to be 3:4. A starts 15 minutes earlier than B. when a meets B, a walks 6 kilometers less than B. It takes 2.25 hours for B to start from B to meet A. how about the speed of a and B and the distance between a and B?

Member a's speed 3x (km / h)
Speed of Party B 4x (km / h)
When we met, B walked for 2.25 hours
A walked for 2.5 hours
A total of 2.5 * 3x = 7.5x
A total of 4x * 2.25 = 9x
B-A = 1.5 x = 6 (km)
X= 4
Speed of a = 12 (km / h)
B's speed = 16 (km / h)
(7.5 + 9) * x = 16.5 * 4 = 66 (km). AB distance

The speed ratio of a and B is known to be 3:4. A starts 15 minutes earlier than B. after 1 hour and 45 minutes, a runs 6 kilometers less than B. (1) what's the speed of a and B? (2) what's the distance between the two places?

(1) Suppose the speed of a is x km / h
x/3×7/4-x/4=6
∴x=18
Then the velocity of B is 18 × 4 / 3 = 24 (km / h)
（2）
（18+24）×7/4+18/4
=78 (km)
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The speed ratio of a and B is 2:3. When they meet, a walks 6 km less than B. It is known that B walks for 1 hour and 30 minutes. The speed of a and B and the distance between two places are calculated

Suppose that the speed of a and B is 2xkm / h and 3xkm / h respectively. From the meaning of the question, we get 2x · (112 + 14) = 3x · 32-6, and the solution is x = 6, 2 × 6 = 12km / h, 3 × 6 = 18km / h, 12 × (112 + 14) + 18 × 32 = 21 + 27 = 48km. A: the speed of a and B is 12km / h and 18km / h respectively, and the distance between the two places is 48km