Q9 of 51 Page 26

Find the value of for which the four points with position vectors and are coplanar.

Formula : -


andthen



(iii) Three vectors are coplanar if and only if


(iv) ifandthen,


Given: -






The four points are coplaner if vector AB⃗,AC⃗,AD⃗ are coplanar.



now, using



⇒ 4(50 – 25) – 6(15 + 20) + (λ + 1)(15 + 40) = 0.


⇒ λ = 1


hence the point are coplanar


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