3-1.Vectors
medium

બે સદિશો $ \overrightarrow P = a\hat i + a\hat j + 3\hat k $ અને $ \overrightarrow Q = a\hat i - 2\hat j - \hat k $ એકબીજાને લંબ હોય,તો $a =$ _________

A

$3$

B

$4$

C

$9$

D

$13$

(AIIMS-2002)

Solution

(a) $\bar P.\bar Q = 0$ 

$⇒$ ${a^2} – 2a – 3 = 0$ $⇒$ $a = 3$

Standard 11
Physics

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