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Comprehension:(Que No. 85 - 88) ++= such that
||=3,||=5 and
||=7
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Question : 85 of 120
Marks:
+1,
-0
Solution:
Here,
||=3,||=5 and
=7 ++⇒+= |+|2=||2+||2 +2||.||cos‌θ ⇒|−|2=||2+||2 +2||.||cos‌θ ⇒72=32+52+2(3)(5)‌cos‌θ ⇒49−9−25=30‌cos‌θ ⇒15=30‌cos‌θ ⇒cos‌θ=1∕2 ∴ θ = π /3
Hence, option (3) is correct.
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