Final answer:
True - The Pythagorean theorem can be used to calculate the length of the resultant vector obtained from the addition of two vectors at right angles.
Step-by-step explanation:
True - We can use the Pythagorean theorem to calculate the length of the resultant vector obtained from the addition of two vectors that are at right angles to each other. The Pythagorean theorem states that in a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. In this case, the two vectors can be considered as the two sides of a right-angled triangle, and the resultant vector is the hypotenuse.