Distance of the point P(→p) from the line →r=→a+λ→b is-
A
∣(→a−→p)+((→p−→a)⋅→b)→b∣→b∣2∣
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B
∣(→b−→p)+((→p−→a)⋅→b)→b∣→b∣2∣
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C
∣(→a−→p)+((→p−→b)⋅→b)→b∣→b∣2∣
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D
None of these.
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Solution
The correct option is A∣(→a−→p)+((→p−→a)⋅→b)→b∣→b∣2∣ Let Q(→q) be the foot of perpendicular drawn from P(→p) to the line →r=→a+λ→b ⇒(→q−→p)⋅→b=0 and →q=→a+λ→b ⇒(→a+λ→b−→p)⋅→b=0 ⇒(→a−→p)⋅→b+λ∣→b∣2=0 ⇒λ=(→p−→a)⋅→b∣→b∣2 ⇒→q−→p=→a+(→p−→a)⋅→b∣→b∣2−→p ⇒∣→q−→p∣=∣(→a−→p)+(→p−→a)⋅→b∣→b∣2∣