If chord joining $t_1$ and $t_2$ on the parabola $y^2=4ax$ is a focal chord then $t_1{t}_2=$

The equation of the chord joining $t_1$ and $t_2$ on the parabola $y^2=4ax$ $y(t_1+t_2)=2x+2a{t}_1{t}_2\cdots \cdots \left(1\right)$

Given equation (1) passes through focus $(a,0)$

$\therefore \text{O}=2a+2a{t}_1{t}_2\Rightarrow t_1{t}_2=-1$