When he pinched two adjacent triangles together and pushed ... a strip of paper so that it may be marked off in 10 equilateral triangles (A). The strip is folded backward along the line ab and ...

A square marked at ... symmetry of order 3. An equilateral triangle fits into its outline three times in a full 360° turn. Image caption, An isosceles triangle has two sides that are equal ...

They often identify them solely based on their resemblance to prototypes: e.g., a shape will be called a triangle if it looks like an equilateral triangle with a horizontal base – all others are ...

Two congruent angles ... You'll like draw a perfect square or rectangle by drawing congruent angles to form the box, and then congruent triangles (equilateral triangles) form the pitched roof.