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Question : 4 of 90
Marks:
+1,
-0
Solution:
Given
||=1,||=4,⋅=2 =2(×)−3Dot product with
on both sides
.=−6 ........(1)
Dot product with
on both sides
‌.=−48‌‌.....(2) ‌⋅=4|×|2+9||2 ‌||2=4[|a|2|b|2−(a⋅)2] +9||2 ‌||2=4[(1)(4)2−(4)]+9(16) ‌||2=4[12]+144 ‌||2=48+144 ‌||2=192 ‌∴cos‌θ=‌ ‌∴cos‌θ=‌ ‌∴cos‌θ=‌ ‌∴cos‌θ=‌ ‌∴cos‌θ=‌ ⇒θ=cos−1(‌)
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