Question

The position vector of P and Q be respectively (i^+3j^-7k^) and (5i^-2j^+4k^) Find PQ|.​

Answer 1

Answer:

${\huge{\pink{↬}}} \:  \: {\huge{\underline{\boxed{\bf{\pink{Answer}}}}}}$

Correct option is C. − 5 √ 162 −5162 Let → r r→ be the direction of → P Q PQ→ Then, → r = Q − P = 4 ^ i − 5 ^ j + 11 ^ k r→=Q−P=4i^−5j^+11k^ Let θ be the angle between → r r→ and Y-axis Then , c o s θ = → r . ^ j | → r | × | → j | cosθ=r→.j^|r→|×|j→| = − 5 ( 16 + 25 + 121 ) 1 2 −5(16+25+121)12 = − 5 √ 162 −5162

Answer 2

${\huge{\pink{↬}}} \:  \: {\huge{\underline{\boxed{\bf{\pink{Answer}}}}}}$

Let → r r→ be the direction of → P Q PQ→ Then, → r = Q − P = 4 ^ i − 5 ^ j + 11 ^ k r→=Q−P=4i^−5j^+11k^ Let θ be the angle between → r r→ and Y-axis Then , c o s θ = → r . ^ j | → r | × | → j | cosθ=r→.j^|r→|×|j→| = − 5 ( 16 + 25 + 121 ) 1 2 −5(16+25+121)12 = − 5 √ 162 −= − 5 ( 16 + 25 + 121 ) 1 2 −5(16+25+121)12 = − 5 √ 162 −5162