Problem Analysis #0

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Problem Statement

Consider the curve CC given in polar coordinates byr=2+cosθ(0θ2π),r = 2 + \cos\theta \qquad (0 \le \theta \le 2\pi),with the origin OO as the pole and the positive xx–axis as the initial line.

  • [(1)] Compute the area of the region enclosed by the curve CC.
  • [(2)] At the point (r,θ)=(4+22,π4), (r,\theta)=\left(\frac{4+\sqrt{2}}{2},\,\frac{\pi}{4}\right), find the slope of the tangent line to the curve CC in the xyxy–coordinate plane. Let aa be the value obtained in part (1). Express the answer from part (2) in the formb+c,b + \sqrt{c},where bb and cc are integers, and let those integers be the definitions of bb and cc. Using these values of aa, bb, and cc, computeabcπ.\frac{abc}{\pi}.\
Ground Truth
-18
Execution Trace
Reasoning Process

[THOUGHT] Let me solve this problem step by step.

Part (1): Area enclosed by the curve For a polar curve r = f(θ), the area is given by: A=1202πr2dθ=1202π(2+cosθ)2dθA = \frac{1}{2}\int_0^{2\pi} r^2 \, d\theta = \frac{1}{2}\int_0^{2\pi} (2 + \cos\theta)^2 \, d\theta

Part (2): Slope of tangent line For a polar curve, the slope in Cartesian coordinates is: dydx=drdθsinθ+rcosθdrdθcosθrsinθ\frac{dy}{dx} = \frac{\frac{dr}{d\theta}\sin\theta + r\cos\theta}{\frac{dr}{d\theta}\cos\theta - r\sin\theta}

Given r = 2 + cos(θ), we have dr/dθ = -sin(θ)

At θ = π/4, I need to compute this slope.

Let me calculate both parts using Python. [/THOUGHT] [PYTHON] import sympy as sp from sympy import pi, cos, sin, sqrt, simplify, integrate, Rational

theta = sp.Symbol('theta')

Part (1): Area calculation

r = 2 + cos(theta) r_squared = r**2

Expand r^2

r_squared_expanded = sp.expand(r_squared) print("r^2 =", r_squared_expanded)

Area = (1/2) * integral from 0 to 2*pi of r^2 dtheta

area_integral = integrate(r_squared, (theta, 0, 2*pi)) area = Rational(1, 2) * area_integral print("Area =", area) print("Area simplified =", simplify(area))

Part (2): Slope of tangent line at theta = pi/4

dy/dx = (dr/dtheta * sin(theta) + r * cos(theta)) / (dr/dtheta * cos(theta) - r * sin(theta))

dr_dtheta = sp.diff(r, theta) print("\ndr/dtheta =", dr_dtheta)

At theta = pi/4

theta_val = pi/4

r_val = r.subs(theta, theta_val) dr_dtheta_val = dr_dtheta.subs(theta, theta_val)

print("r at pi/4 =", r_val) print("dr/dtheta at pi/4 =", dr_dtheta_val)

Numerator: dr/dtheta * sin(theta) + r * cos(theta)

numerator = dr_dtheta_val * sin(theta_val) + r_val * cos(theta_val)

Denominator: dr/dtheta * cos(theta) - r * sin(theta)

denominator = dr_dtheta_val * cos(theta_val) - r_val * sin(theta_val)

print("\nNumerator =", numerator) print("Denominator =", denominator)

slope = numerator / denominator slope_simplified = simplify(slope) print("\nSlope =", slope_simplified)

Let's rationalize and simplify further

slope_rationalized = sp.nsimplify(slope_simplified, rational=False) print("Slope rationalized =", slope_rationalized)

Let's expand this more carefully

slope_expanded = sp.simplify(sp.expand(slope_simplified)) print("Slope expanded =", slope_expanded) [/PYTHON]

Tool Output
[PYTHON OUTPUT] r^2 = cos(theta)**2 + 4*cos(theta) + 4 Area = 9*pi/2 Area simplified = 9*pi/2 dr/dtheta = -sin(theta) r at pi/4 = sqrt(2)/2 + 2 dr/dtheta at pi/4 = -sqrt(2)/2 Numerator = -1/2 + sqrt(2)*(sqrt(2)/2 + 2)/2 Denominator = -sqrt(2)*(sqrt(2)/2 + 2)/2 - 1/2 Slope = -2 + sqrt(2) Slope rationalized = -2 + sqrt(2) Slope expanded = -2 + sqrt(2) [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] From the Python calculations:

Part (1): The area enclosed by the curve is a=9π2a = \frac{9\pi}{2}

Part (2): The slope of the tangent line is 2+2-2 + \sqrt{2}, which can be written as b+cb + \sqrt{c} where b=2b = -2 and c=2c = 2.

Now I need to compute: abcπ=9π2(2)2π=9π(2)π=9(2)=18\frac{abc}{\pi} = \frac{\frac{9\pi}{2} \cdot (-2) \cdot 2}{\pi} = \frac{9\pi \cdot (-2)}{\pi} = 9 \cdot (-2) = -18

Wait, let me recalculate: abcπ=abcπ=9π2(2)2π=9π(2)π=18\frac{abc}{\pi} = \frac{a \cdot b \cdot c}{\pi} = \frac{\frac{9\pi}{2} \cdot (-2) \cdot 2}{\pi} = \frac{9\pi \cdot (-2)}{\pi} = -18

The answer is 18-18. [/THOUGHT]

\boxed{-18}

Final Model Output
-18

Comparative Analysis (P0) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
316.3
Deepseek-V3.2
81.3
Llama-VARCO-8B-Instruct
49.3
GPT-5.1 (high)
38.4
HCX-007(high)
36.4
Solar-Pro-2 (31B)(high)
30.2
Grok-4.1-fast
21.1
Claude-Opus-4.5
18.0
A.X-4.0 (72B)
16.6
EXAONE-4.0.1-32B (high)
6.7

Avg Token Usage

Gemini-3-Pro-Preview
12238.0
Deepseek-V3.2
7244.0
Solar-Pro-2 (31B)(high)
6632.0
HCX-007(high)
6397.0
Grok-4.1-fast
6290.0
GPT-5.1 (high)
4822.0
Claude-Opus-4.5
4528.0
Llama-VARCO-8B-Instruct
4316.0
EXAONE-4.0.1-32B (high)
4306.0
A.X-4.0 (72B)
3605.0