c=λ(b×(a×b))=λ((b⋅b)a−(a⋅b)b)=λ(11a−2 b)=λ(11i+22j+33k−6i−2j+2k)=λ(5i+20j+35k)=5λ(5i+4j+7k)= Given c⋅a=5=5λ(1+8+21)=5=λ=301⇒c=61(i+4j+7k)c=61+16+49=611
JEE Main 2025 — Mathematics Vectors & 3D Geometry
Let a=i^+2j^+3k^,b=3i^+j^−k^ and c be three vectors such that c is coplanar with a and b. If the vector C is perpendicular to b and a⋅c=5, then ∣c∣ is equal to
Held on 24 Jan 2025 · Verified 6 Jul 2026.
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