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If ∣a⃗∣=5|\vec{a}| = 5, ∣b⃗∣=6|\vec{b}| = 6 and a⃗.b⃗=18\vec{a}.\vec{b} = 18, then value of ∣a⃗×b⃗∣|\vec{a} \times \vec{b}| is

Solution

✅ Correct Option: 4

∣a⃗×b⃗∣2+(a⃗⋅b⃗)2=∣a⃗∣2∣b⃗∣2|\vec{a}\times\vec{b}|^2 + (\vec{a}\cdot\vec{b})^2 = |\vec{a}|^2|\vec{b}|^2.

So ∣a⃗×b⃗∣2=25⋅36−182=900−324=576|\vec{a}\times\vec{b}|^2 = 25\cdot 36-18^2 = 900-324 = 576, giving ∣a⃗×b⃗∣=24|\vec{a}\times\vec{b}| = 24.

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