Skip to main contentSkip to solution

If A=[cos⁡αsin⁡α−sin⁡αcos⁡α]A = \begin{bmatrix}\cos\alpha & \sin\alpha\\-\sin\alpha & \cos\alpha\end{bmatrix}, then the value of 1000∣An∣+2∣A∣1000|A^n| + 2|A| for a positive integer nn, is equal to

Solution

✅ Correct Option: 4

∣A∣=cos⁡2α+sin⁡2α=1|A|=\cos^2\alpha+\sin^2\alpha=1.

So ∣An∣=∣A∣n=1|A^n|=|A|^n=1 for every positive integer nn.

Then 1000∣An∣+2∣A∣=1000(1)+2(1)=10021000|A^n|+2|A|=1000(1)+2(1)=1002.

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question