Question

the following points from an isosceles triangle 
          1.(-2,0),(4,0)and(1,3)
          2.(1,-2),(-5,1)and(1,4)
          3.(-1,-3),(2,-1)and(-1,1)
     please urgent

Answer 1

Distance between points P(a,b) and Q(c,d) is = √[ (a-c)²+(b-d)² ]

Find the lengths of the sides. If you find two sides are equal then it is an isosceles triangle. Let us say the first point is P, second Q and the third R

1.  PQ = √[(-2-4)²+(0-0)²] = 6          QR = √[(4-1)²+(0-3)²] = √18
     PR = √[(-2-1)² +(0-3)² ] = √18              PR = QR

2. PQ = √[(1+5)²+(-2-1)²] = √45          QR = √[(-5-1)²+(1-4)²] = √45
        PQ = QR

3. PQ = √[(-1-2)²+(-3+1)²] = √13          QR = √[(2+1)²+(-1-1)²] = √13
     PQ = QR

so isosceles Δ