Question

What is the perimeter of a triangle with coordinates A(-1,5) B(-1,1) and C(2,1)

Answer 1

...you know the formula
`√((x2-x1)^2+(y2-y1)^2)`

AB :

`√((-1-(-1))^2+(1-5)^2) =√((-1+1)^2+(-4)^2) =√(16) =4\\\\`

BC :

`√((2-(-1))^2 +(1-1)^2) =√(2+1)^2+0) =√(9) =3`

CA :

`√((-1-2)^2+(5-1)^2) =√((-3)²+(4)^2) =√(9+16) =√(25) =5`

perimeter = 4+3+5 = 7

Explanation: