
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
A circle of radius $r$ and a right-angled isosceles triangle are drawn such that one of the shorter sides of the triangle is a diameter of the circle. What is the shaded area?
A) $\sqrt{2} r$
B) $r^{2}$
C) $2 \pi r$
D) $\frac{\pi r^{2}}{4}$
E) $(\sqrt{2}-1) \pi r^{2}$

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