MATLAB: How to get a continuous line through two scatter plots

line

Hi all,
I am trying to get get a continuous line to pass through the two scatter points in my MatLab code. I have currently joined to the two points together but I need the line to continue so I can get a point of intersection with the line and the curve. 
Lr=(0:0.02:1.4);
Kr=(1-0.14.*Lr.^2).*(0.3 + 0.7.*exp(-0.65*Lr.^6));
%SteelA
Lr1=0;
Lr2=0.7356;
Kr1=0.01048;
Kr2=0.7333;
plot(Lr,Kr,'LineWidth',3);
legend('Limit');
hold on;
title('Failure Assessment Diagram (FAD) for Steel A');
xlabel('Lr');
ylabel('Kr');
hold on;
scatter(Lr1,Kr1,'*','r')
hold on;
scatter(Lr2,Kr2,'*','g')
hold on;
plot([Lr1 Lr2],[Kr1 Kr2])
grid on;
legend ('R6 Kr curve','Lr(s)=0, Kr(s)(Steel A)', 'Lr(p), Kr(p+s)(Steel A)')

Best Answer

Another approach: 
Lr=(0:0.02:1.4);
Kr=(1-0.14.*Lr.^2).*(0.3 + 0.7.*exp(-0.65*Lr.^6));
%SteelA
Lr1=0;
Lr2=0.7356;
Kr1=0.01048;
Kr2=0.7333;
B = [Lr1 1;Lr2 1] \ [Kr1; Kr2];                                 % Linear Regression
LExt = [Lr(:) ones(size(Lr(:)))] * B;                           % Extend Line For All ‘Lr’
Lr_int = interp1(LExt - Kr(:), Lr, 0);                          % ‘Lr’ Value At Intersection
Krfcn = @(Lr) (1-0.14.*Lr.^2).*(0.3 + 0.7.*exp(-0.65*Lr.^6));   % ‘Kr’ Anonymous Function
Kr_int = Krfcn(Lr_int);                                         % ‘Kr’ Value At At Intersection
figure
h(1) = plot(Lr,Kr,'LineWidth',3);
hold on;
title('Failure Assessment Diagram (FAD) for Steel A');
xlabel('Lr');
ylabel('Kr');
h(2) = scatter(Lr1,Kr1,'*','r');
h(3) = scatter(Lr2,Kr2,'*','g');
plot([Lr1 Lr2],[Kr1 Kr2])
h(4) = plot([Lr2 Lr_int], [Kr2 Kr_int], ':r');
h(5) = plot(Lr_int, Kr_int,'pm', 'MarkerFaceColor','m', 'MarkerSize',8);
grid on;
legend (h, 'R6 Kr curve','Lr(s)=0, Kr(s)(Steel A)', 'Lr(p), Kr(p+s)(Steel A)', 'Extended Line', 'Intersection', 'Location','S')
EDIT — (19 Apr 2020 at 18:21)
Added plot image:
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