Definition of an even function: $f(a) = f(−a)$
Definition of an odd function: $f(−a) = −f(a)$

$(a)^²= a^²$
$f(−a) =$ $(−a)^²=$ $a^²..........$ $f(a) =$ $f(−a)$ it's even!
$−f(a) = −$$(a)^²=$ $−a^²...........$$f(−a) ≠$ $−f$ (a) it's NOT odd.

Refer to hint and steps in part (a).

Refer to hint and steps in part (a).

Even functions are symmetrical over the $y$-axis.
Odd functions are symmetrical about the origin.

Sketch a graph of $\text{sin}x$ and describe the symmetry.