Understanding Eigenvalues and Eigenvectors in Reflection Matrices

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Homework Statement



Let A be a matrix corresponding to reflection in 2 dimensions across the line generated by a vector v . Check all true statements:

A. lambda =1 is an eigenvalue for A
B. Any vector w perpendicular to v is an eigenvector for A corresponding to the eigenvalue lambda =1.
C. The vector v is an eigenvector for A corresponding to the eigenvalue lambda =1.
D. Any vector w perpendicular to v is an eigenvector for A corresponding to the eigenvalue lambda =−1.
E. lambda =−1 is an eigenvalue for A
F. None of the above

The Attempt at a Solution



I honestly have no clue how to do this question. Can somebody explain to me what the question is asking and how to solve it?
 
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Do you know what the definition of an eigenvalue/eigenvector is? Think about the case where A just reflects over the x-axis first in R2 in order to get a handle on what the question is asking
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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