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1.公园里有3艘游戏小艇A、B、C在进行水上娱乐表演,它们绕着半径为30米的一个圆周相互追逐。某一时刻,3艘艇之间的相对位置构成了某种队列形状:AB间的直线距离是BC的3/4,CA间的直线距离是AB的5/3。求:BC间的直线距离是多少? 2.一艘常规潜艇以20节的航速向前行驶,一艘核潜艇则以30节的航速从其后15000码处用声呐系统开始追踪。声呐仪先发出声波,声波传至目标被反射回来,声呐仪测出这中间一来一回
1. There are 3 game boats A, B and C in the park performing water entertainment. They are chasing each other around a circle with a radius of 30 meters. At some point, the relative position between the three boats constitutes a certain queue shape: the straight line distance between AB is 3/4 of BC, and the straight line distance between CA is 5/3 of AB. What is the straight-line distance between BC? 2. A conventional submarine travels at a speed of 20 knots. A nuclear submarine begins tracking with a sonar system at a speed of 30 knots from the next 15,000 yards. The sonic meter emits sound waves first. The sound waves reach the target and are reflected back. The sonic meter measures the middle and back.