Question

. Prove or disprove that the points A(-1, 3), B(-3, 1) and C(1, -1) make up an equilateral
triangle.

Answer 1

Find the distance between A and B, then B to C. If same, try A to C.
do that by use distance formula \(\Large d = \sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\)

Answer 2

property of equilateral triangle 3 equal sides, 3 equal angles
using the information in the post above to get the length of the sides then if AB = BC =AC then ABC is an equilateral triangle