Answer
a). $(1)$ the tension increases.
b). $3465N$ in each cable.
Work Step by Step
a). The tension will increase (1).
Because as $\theta$ decreases, $sin\theta$ also decreases.
However, the vertical component of both the cables together is $2Tsin\theta$ which is equal to $mg$ is fixed.
So, if $sin\theta$ decreases, T should increase.
b). $2Tsin45^{\circ}=mg$
$T=\frac{500\times9.8}{2\times\frac{1}{\sqrt 2}}=3465N$