Plot a curve in the region defined
I have the following region :
p, t= var('p t')
a=(-2*p*t^2-p^2*t)+(2*t*p-p^2)+t+1
b=(p*t^2+2*p^2*t)+(2*t*p-t^2)-p+1
c=(p*t^2-p^2*t)+(t^2+2*t*p+p^2)+t-p #3 sides (a,b,c) in terms of theta and phi
region_plot([a+b>=c, b+c>=a, c+a>=b], (t,-2,2), (p,-2,2))
And I want to plot a curve C=t*p*(t-p)+t*p+2*(t-p)-1
on the region in first quadrant. How am I suppose to do that.