Let $A=\left[\begin{array}{ccc}b^2+c^2 & a^2 & a^2 \\ b^2 & c^2+a^2 & b^2 \\ c^2 & c^2 &…
Let $A=\left[\begin{array}{ccc}b^2+c^2 & a^2 & a^2 \\ b^2 & c^2+a^2 & b^2 \\ c^2 & c^2 & a^2+b^2\end{array}\right]$. If
$a=\sin \frac{\pi}{6}, b=\cos \frac{\pi}{4}$ and $c=\cot \frac{\pi}{2}$, then $A$ is
- Symmetric matrix
- Skew-Symmetric matrix
- Singular matrix
- Non-singular matrix
Solution
$
\begin{aligned}
& \text { Given, } a=\sin \frac{\pi}{6}=\frac{1}{2}, b=\cos \frac{\pi}{4}=\frac{1}{\sqrt{2}}, \\
& c=\cot \frac{\pi}{2}=0 \\
& \because \quad|A|=\left|\begin{array}{lll}
\frac{1}{2} & \frac{1}{4} & \frac{1}{4} \\
\frac{1}{2} & \frac{1}{4} & \frac{1}{2} \\
0 & 0 & \frac{3}{4}
\end{array}\right| .
\end{aligned}
$
Here, $c_1=2 c_2$
$
\therefore \quad|A|=0
$
$\therefore A$ is singular matrix
Asked in: AP EAMCET 2022 (07 Jul Shift 2)
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