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] I will:

  1. Use the polar area formula (a = \frac12 \int_0^{2\pi} r^2 , d\theta) with (r = 2+\cos\theta).
  2. Use the polar slope formula (\frac{dy}{dx} = \frac{r' \sin\theta + r\cos\theta}{r' \cos\theta - r\sin\theta}) and evaluate at (\theta = \frac{\pi}{4}), where (r = \frac{4+\sqrt2}{2}).
  3. Simplify the slope into the form (b + \sqrt{c}) and read off integers (b,c).
  4. Compute (\frac{abc}{\pi}) using the area (a) from (1).

I’ll use Sympy to carry out the integrals and algebra exactly. [/THOUGHT] [PYTHON] import sympy as sp

Define symbols

theta = sp.symbols('theta', real=True) r = 2 + sp.cos(theta)

Part (1): area

area = sp.simplify(sp.Rational(1,2) * sp.integrate(r**2, (theta, 0, 2*sp.pi))) print("Area a =", area)

Part (2): slope dy/dx at the given point (theta = pi/4)

theta0 = sp.pi/4 r0 = r.subs(theta, theta0) dr_dtheta = sp.diff(r, theta) dr0 = dr_dtheta.subs(theta, theta0)

slope = sp.simplify((dr_dthetasp.sin(theta) + rsp.cos(theta)) / (dr_dthetasp.cos(theta) - rsp.sin(theta))) slope0 = sp.simplify(slope.subs(theta, theta0)) print("Slope at theta=pi/4 =", slope0)

Express slope as b + sqrt(c)

b, c = sp.symbols('b c', integer=True)

Let's see if slope0 can be written as A + B*sqrt(2) first

slope_simplified = sp.nsimplify(slope0, [sp.sqrt(2), sp.sqrt(3), sp.sqrt(5)]) print("nsimplify slope:", slope_simplified)

It appears to be of form p + q*sqrt(2); we need b + sqrt(c).

If it's p + qsqrt(2), then set qsqrt(2) = sqrt(c) => c = 2*q^2 if q>0.

p, q = sp.symbols('p q') p_q_form = sp.together(slope_simplified).expand() print("Expanded slope form:", p_q_form)

Manually decompose assuming form A + B*sqrt(2)

A = sp.simplify(sp.radsimp(sp.simplify(sp.nsimplify(slope0 - sp.sqrt(2)*0, [sp.sqrt(2)])))) print("Test A (not final):", A)

Directly solve for coefficients in basis {1, sqrt(2)}

A_coeff = sp.simplify(sp.nsimplify((slope0.expand().rewrite(sp.sqrt) - sp.sqrt(2)*0), [sp.sqrt(2)])) print("A_coeff tentative:", A_coeff)

Let's just ask sympy to express in a + b*sqrt(2)

a_sym, b_sym = sp.symbols('a_sym b_sym') A_expr = sp.solve(sp.Eq(a_sym + b_sym*sp.sqrt(2), slope0), (a_sym, b_sym))[0] print("Decomposition (a_sym, b_sym) with sqrt(2):", A_expr)

a_sym_val, b_sym_val = A_expr

Now want b + sqrt(c) with integers; set b = a_sym_val, sqrt(c) = b_sym_val*sqrt(2)

b_int = sp.simplify(a_sym_val) sqrt_c_expr = sp.simplify(b_sym_val*sp.sqrt(2)) print("b_int =", b_int, ", sqrt_c_expr =", sqrt_c_expr)

Then c is square of coefficient inside sqrt_c_expr: sqrt_c_expr = ksqrt(2) => sqrt(c)=ksqrt(2) => c=2*k^2

k = sp.simplify(sp.factor(sp.sqrt(2)b_sym_val / sp.sqrt(2))) # k = b_sym_val k = b_sym_val c_int = sp.simplify(2k**2) print("c_int =", c_int)

Now compute abc/pi

a = area b_val = sp.simplify(b_int) c_val = sp.simplify(c_int) abc_over_pi = sp.simplify(ab_valc_val/sp.pi) print("abc/pi =", abc_over_pi) [/PYTHON]

Tool Output
[PYTHON OUTPUT] Area a = 9*pi/2 Slope at theta=pi/4 = -2 + sqrt(2) nsimplify slope: -2 + sqrt(2) Expanded slope form: -2 + sqrt(2) Test A (not final): -2 + sqrt(2) A_coeff tentative: -2 + sqrt(2) Decomposition (a_sym, b_sym) with sqrt(2): (-sqrt(2)*b_sym - 2 + sqrt(2), b_sym) b_int = -sqrt(2)*b_sym - 2 + sqrt(2) , sqrt_c_expr = sqrt(2)*b_sym c_int = 2*b_sym**2 abc/pi = 9*b_sym**2*(-sqrt(2)*b_sym - 2 + sqrt(2)) [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] From the Python results: (a = \frac{9\pi}{2}), slope (= -2 + \sqrt{2}), so (b=-2) and (c=2). Then [ \frac{abc}{\pi} = \frac{\left(\frac{9\pi}{2}\right)(-2)(2)}{\pi} = -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