Resultant of two vectors P and Q is of magnitude A. If Q is reversed, then the resultant is of magnitude B. The value of A² + B² is (a) P² + Q² (b) P² - Q² (c) 2(P² + Q²) (d) 2(P² - Q²)

Answer: (c). A² = P² + Q² + 2PQcos θ Reversing Q: B² = P² + Q² - 2PQcos θ Adding: A² + B² = 2(P² + Q²) So the answer is (c).

Resultant of two vectors P and Q is of magnitude A. If Q is reversed… | MHT CET 2026 (17 Apr, Shift 1)

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Addition & Subtraction of Vectors

Resultant of two vectors $\vec{P}$ and $\vec{Q}$ is of magnitude A. If $\vec{Q}$ is reversed, then the resultant is of magnitude B. The value of $A^2 + B^2$ is

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Answer: (c)

$A^2 = P^2 + Q^2 + 2PQ\cos\theta$
Reversing $\vec{Q}$ : $B^2 = P^2 + Q^2 - 2PQ\cos\theta$
Adding: $A^2 + B^2 = 2(P^2 + Q^2)$
So the answer is (c).

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