Question

1. cho A(2;-5), B(4;-2). Tính AB

2. cho C(3;-1), D(1;-2). Tính CD

Answer 1

1: 

A(2;-5); B(4;-2)

=>\(AB=\sqrt{\left(4-2\right)^2+\left(-2+5\right)^2}=\sqrt{2^2+3^2}=\sqrt{13}\)

2: C(3;-1); D(1;-2)

=>\(CD=\sqrt{\left(1-3\right)^2+\left(-2+1\right)^2}=\sqrt{\left(-2\right)^2+\left(-1\right)^2}=\sqrt{5}\)

Answer 2

`A(2;-5), B(4;-2)`

`=> vec{AB} = (4 - 2; -2 - (-5)) = (2; 3)`

`=> AB = sqrt{2^2 + 3^2} = sqrt{13}`

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`C(3;-1), D(1;-2)

`=> vec{CD} = (1-3;-2-(-1)) = (-2;-1)`

`=> CD = sqrt{(-2)^2 + (-1)^2} = sqrt{5}`