two people start off to walk directly away from each other.they each walk for 4 kilometers then
问题描述：
two people start off to walk directly away from each other.they each walk for 4 kilometers then
turn directly to their right and walk for another 3 kilometers.how far apart are they?
答
they are apartfrom each other 10 kilometers
distance=2*v(4*4+3*3）=2*5=10