Why zero-padding not visualized in this signal?

Attached the image produced by the simple code below:

t      = -10:.1:10-.1;
tz     = [zeros(1,50) t zeros(1,50)];
figure
plot(tz,cos(2*pi*tz))

I'd like to know what I can do to edit this way of zero-padding.

Answer 1

[Ezz El-din Abdullah]

Thank you. I have realized that I should zero-pad the y-axis not the x-axis.