Practicing Success
Practicing Success
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If $A=\begin{bmatrix}\cos θ &\sin θ\\-\sin θ&\cos θ\end{bmatrix}$, then $A^2 = 1$, is true for |
$θ=0$ $θ=\frac{π}{4}$ $θ=\frac{π}{2}$ none of these |
$θ=0$ |
We have, $A^2=\begin{bmatrix}\cos 2θ &\sin 2θ\\-\sin 2θ&\cos 2θ\end{bmatrix}$ $∴A^2=I= \cos 2θ=1$ and $\sin 2θ=0⇒ θ=0$. |
