According to the meaning of the question, when the wind force in the typhoon center is 12, the wind force 200 kilometers away from the center is 4.
If point A is AD⊥BC in D, then point D is the closest point of typhoon center to city A.
It is known that ABC = 30, AB=240 km,
Available: AD = 120km? & lt? 200 kilometers,
Therefore, City A will be affected by the typhoon.
2、
Suppose that when city A begins to be affected by the typhoon, the center of the typhoon is point E; When city A is affected by typhoon, the typhoon center is point F; Yes: AE=AF=200 kilometers.
Available: DE = DF = 160km, EF = 320km.
Therefore, the duration of typhoon affecting city A is: 320/20? =? 16? hour
3、
Because, when the typhoon center reaches the nearest D point to A city, A city is the most affected by the wind.
So, it can be calculated: 12? -? 120/25? =? 7.2? ;
Taking the whole number, we can get: What is the maximum wind force affected by typhoon in City A? 7? Level.