Question

Which statement is not true? All isosceles triangles are also called lateral triangles. All equilateral triangles are also isosceles.

1) All isosceles triangles are also called lateral triangles.
2) All equilateral triangles are also isosceles.
3) None of the above

Answer 1

The incorrect statement is that all isosceles triangles are called lateral triangles. This is not a standard term in geometry, while it is true that all equilateral triangles are isosceles since they have all equal sides.

Step-by-step explanation:

The question is discussing properties of isosceles and equilateral triangles, which are concepts in geometry, a branch of mathematics. An isosceles triangle is defined as a triangle with at least two sides of equal length. An equilateral triangle is a particular kind of isosceles triangle where all three sides are of equal length, making all three internal angles equal to 60 degrees each.

Now, considering the given statements:

1. All isosceles triangles are also called lateral triangles.
2. All equilateral triangles are also isosceles.
3. None of the above.

The statement that says 'All isosceles triangles are also called lateral triangles' is not true. 'Lateral' generally refers to the sides, but it is not a standard term used to describe isosceles triangles in geometry. The second statement 'All equilateral triangles are also isosceles' is true because equilateral triangles do have two sides of equal length—in fact, all three sides and angles are equal.

Therefore, the incorrect statement among the options provided is the first one, asserting that all isosceles triangles are called lateral triangles.