Final answer:
The question incorrectly combines military tactics with a physics problem, but addressing the part relevant to the Pythagorean theorem, the answer is true: the theorem can be used to calculate the length of a resultant vector of two vectors at right angles.
Step-by-step explanation:
The question seems to be from a military tactics context and involves the use of terms like friendly force posture, commanders, JTACs (Joint Terminal Attack Controllers), and aircrew which are unrelated to the Pythagorean theorem. However, part of the question has been mixed with another topic, specifically one that concerns the Pythagorean theorem in physics.
The Pythagorean theorem states that in a right-angled triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides. Thus, given two vectors that are at right angles, the Pythagorean theorem can be used to calculate the resultant vector. The answer, therefore, to the question 'True or False - We can use the Pythagorean theorem to calculate the length of the resultant vector obtained from the addition of two vectors which are at right angles to each other' is a. True.