Question

若A(1,y)与B(-3,2)两点间的距离等于5,求y的值

Answer 1

2点距离用勾股定理求出:

S=√{[1-(-3)]^2+(Y-2)^2}=5

[1-(-3)]^2+(Y-2)^2=25

16+(Y-2)^2=25

(Y-2)^2=9

Y-2=3 或Y-2=-3

解得Y=5 或Y=-1