
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
In the diagram, $O$ is the center of a circle with radii $OR=OS=10$. In the shaded region, arc $RS$ corresponds to a $270^\circ$ central angle. What is the perimeter of the shaded region?

[asy]
size(100);
import graph;
label("$R$",(-1,0),W); label("$O$",(0,0),NE); label("$S$",(0,1),N);

fill(Arc((0,0),1,90,360)--cycle,mediumgray);
draw(Arc((0,0),1,90,360));
fill((0,0)--(-1,0)--(0,1)--cycle,white);
draw((-1,0)--(0,0)--(0,1));
draw((-0.1,0)--(-0.1,0.1)--(0,0.1));

[/asy]

Present the answer in LaTex format: \boxed{Your answer}
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