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JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant

વિધાનો :
I: જો\(\left|\begin{array}{ccc}1 & \cos \alpha & \cos \beta \\ \cos \alpha & 1 & \cos \gamma \\ \cos \beta & \cos \gamma & 1\end{array}\right|=\left|\begin{array}{ccc}0 & \cos \alpha & \cos \beta \\ \cos \alpha & 0 & \cos \gamma \\ \cos \beta & \cos \gamma & 0\end{array}\right|\), તો \(\cos ^2 \alpha+\cos ^2 \beta+\cos ^2 \gamma=\frac{3}{2}\), અને
II: જો \(\left|\begin{array}{ccc}x^2+x & x+1 & x-2 \\ 2 x^2+3 x-1 & 3 x & 3 x-3 \\ x^2+2 x+3 & 2 x-1 & 2 x-1\end{array}\right|=p x+q\), તો \(p ^2=196 q ^2\),

  1. A બંને ખોટાં છે
  2. B માત્ર II સાચું છે
  3. C બંને સાચાં છે
  4. D માત્ર I સાચું છે
Verified Solution

Answer & Solution

Correct Answer

(A) બંને ખોટાં છે

Step-by-step Solution

Detailed explanation

Let \(\cos \alpha= x\) \(\cos \beta=y\) \(\cos \gamma= z\) \(\left|\begin{array}{lll}0 & x & y \\ x & 0 & z \\ y & z & 0\end{array}\right|=\left|\begin{array}{lll}1 & x & y \\ x & 1 & z \\ y & z & 1\end{array}\right|\) Expending both sides, we get \(x^2+y^2+z^2=1\) i.e.…
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