OH NO!!!!
Autistic Madoka has trapped Rena in the center of a perfectly circular pond. Autistic Madoka is waiting on the perimeter of the pond and can run exactly 4x faster than Rena can swim, and will always move to the part of the shore that is closest to Rena as possible

if Rena can touch land for even a split second before Autistic Madoka catches her she can escape, but if Madoka is waiting for her when she arrives then she'll kill Rena!

HOW TF CAN RENA ESCAPE TO SAVE US???

note: if Autistic Madoka can take two paths of the same distance to the location she'll flip a coin and choose one

Autistic madoka can change directions instantly!

Here's what happens if Rena always swims towards the closest shore and away from Autistic Madoka. fact is a ponderation factor. If fact=0, she swims towards the shore opposite to where Autistic Madoka stands; if fact=1, she swims away from Autistic Madoka and if fact=[tex:infty], she swims towards the closest shore.
It seems she can't survive using this strategy if Autistic Madoka runs faster than about 3.864 times her swimming speed, but the strategy isn't optimal since she might as well swim straight near the end rather than make this weird curve.
You can have my unoptimized Italian code if you want to play with it.

If Rena is less than 1/4 R away from the center, she can swim in a circle around the center at a faster angular speed than Autistic Madoka can run around the perimeter. This way Rena can swim into a position where her distance from the center is infinitesimally near 1/4 R and Autistic Madoka is infinitesimally near the point on the shore that is the farthest away from Rena. From here, Rena has to swim 3/4 R straight to reach the shore and Autistic Madoka would have to run π*R to catch Madoka. If Rena's speed is v and Autistic Madoka's speed is 4*v, the time Rena has to swim is 3/4 R/v and the time Autistic Madoka would have to run is π*R/(4*v) = π/4 R/v. Since 3 < π, Rena reaches the shore before Autistic Madoka can catch her.

P64523
As Rena starts fleeing from the pond Autistic Madoka yells after her
>Not so fast, you think you've escaped but first you must tell me what is the maximum speed difference between your swimming and my running that would still allow you to escape?

if Rena doesn't answer correctly then Autistic Madoka will snap her fingers causing Rena to die instantly

Hint: The ratio is [bold: not] [tex: \pi+1].

The problem I'm trying to figure out is how to drown both of them quietly and hide the bodies so that no one will know before they decompose.

Given: alligator, duct-tape, ball gag

ball gag + (duct-tape) * alligator = win

P64541
THIS, fuck tranime

P64541
55% basted jd
touching cancerime is cring aids
555 gallon 5B + elektron + M4 buster = win
>drowning
in flames powerful enough to melt calcium

P64540
Using a mix of P64523's and P64521's strategies, I manage to escape as long as Autistic Madoka's speed is less than 4.373. It's only a numerical solution though, and Rena's trajectory is suboptimal anyway.