Q.
The value of Δ=∣∣12cosθ4cos2θ−1sin3θsin6θsin9θsin3θsin32θsin33θ∣∣ is equal to
1339
213
NTA AbhyasNTA Abhyas 2020Matrices
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Solution:
Multiplying C1 by 3sinθ and dividing Δ by 3sinθ , we get, Δ=3sinθ1∣∣3sinθ3sin2θ3sin3θsin3θsin6θsin9θsin3θsin32θsin33θ∣∣ ∵3sinθ(4(cos)2θ−1)=3sinθ(3−4(sin)2θ)=3(sinθ−4(sin)3θ)=3sin3θ
Now, applying C1↔C1−4C3 C1 becomes identical with C2
Hence, Δ=0