Final answer:
Based on the properties of vectors being perpendicular and parallel, when vectors are perpendicular, they can form a right-angled triangle. The Pythagorean theorem is used to relate the lengths of the legs and hypotenuse in such triangles, confirming the triangles are right-angled.
Step-by-step explanation:
To determine which statement is true about the triangles in question, we must refer to the properties of triangles and vectors provided. Since it's mentioned that vectors are perpendicular to each other, forming a 90° angle, and another case where vectors are parallel, we'll focus on perpendicularity and parallelism.
Given that two vectors are perpendicular, they can form a right-angled triangle with their respective x and y components, where these components act as the legs of the triangle. The relationship between these perpendicular components can be described using the Pythagorean theorem, which states that for a right triangle with legs 'a' and 'b', and hypotenuse 'c', the theorem is expressed as a² + b² = c². This is applicable to find the length of the resultant vector (hypotenuse 'c') when the vectors are at right angles to each other.
Hence, applying these principles, the correct answer would be (c) They are right-angled triangles.