For the following questions answer them individually
If $$A = \left(\begin{array}{c}0 & -2\\ 2 & 0\end{array}\right)$$ and $$B = \left(\begin{array}{c}1 & 0\\ 0 & -1\end{array}\right)$$, then AB + BA =
If A, B are square matrices of same order such that $$B = -A^{-1} BA$$, then $$(A + B)^2 =$$
In the figure below if $$\angle ABC = \angle BDC = 90^\circ, BD = AD$$, then $$\angle BCD = $$
If two circles of radii 5 em and 12 em touch each other externally, then the distance between their centres (in centimetres) is
The area (in square units) of the polygon whose vertices taken in order are (0, 0), (6,0), (6, 6), (4, 4) and (0, 6) is