Question

Which statement is always true, based on the Venn diagram?

If a triangle is equilateral, then the triangle must also be isosceles.
If a triangle is isosceles, then the triangle must also be equilateral.
If a triangle is isosceles, then the triangle will never also be equilateral.
If a triangle is equilateral, then the triangle will not always be isosceles.

Answer 1

"If a triangle is equilateral, then the triangle must also be isosceles."

Reason: the set of equilateral triangles is entirely inside the set of isosceles triangles (an equilateral triangle has at least two equal sides), so every equilateral triangle is isosceles. The other statements are false.