Here we plot the intersection of three functions `g(8,pc)`

, `g(10,pc)`

, `g(20,pc)`

respect to`f(pc)`

.

For example,if we want to find the intersetion of `g(8,pc)`

and `y=f(x)`

when we plot `g(8,pc)`

, we can set the `MeshFunction`

of `g(8,pc)`

to `y-f(x)`

,that is `MeshFunctions -> {#2 - f(#1) &}, Mesh -> {{0}}`

```
np = 2;
f(pc_) := 1;
q(d_, pc_) := (pc/(100*0.48))*
Sum(((Pi/4)*(d - (2*n*0.48))^2), {n, 1, np});
p(d_) := Sum(Pi*(d - (2*n - 1)*0.48), {n, 1, np});
g(d_, pc_) := q(d, pc)/p(d);
plot = Plot(Evaluate(Table(g(d, pc), {d, {8, 10, 20}})), {pc, 0, 50},
MeshFunctions -> {#2 - f(#1) &}, Mesh -> {{0}},
MeshStyle -> {PointSize(Large), Automatic}, PlotRange -> All,
AxesLabel -> {"%", "li/lp"},
FrameLabel -> {Style("pc", 12, Bold), Style("li/lp", 12, Bold)},
PlotLabels -> {"d=8", "d=10", "d=20"}, PlotTheme -> "Scientific",
GridLines -> Automatic, PlotLabel -> "Razão comprimentos")
Show(plot, Plot(f(pc), {pc, 0, 50}))
```

On the other hand, we can also set three pure functions when we plot `f(pc)`

to get the three intersection.

```
np = 2;
f(pc_) := 1;
q(d_, pc_) := (pc/(100*0.48))*
Sum(((Pi/4)*(d - (2*n*0.48))^2), {n, 1, np});
p(d_) := Sum(Pi*(d - (2*n - 1)*0.48), {n, 1, np});
g(d_, pc_) := q(d, pc)/p(d);
Plot(f(pc), {pc, 0, 50},
MeshFunctions ->
Table(Function(pc, g(d, pc) - f(pc) // Evaluate), {d, {8, 10, 20}}),
Mesh -> {{0}}, MeshStyle -> Directive(PointSize(Large), Red))
```