Problem Analysis #0

GPT-5.1 (high) · Run 1

38.45s
4,822 toks
Problem Statement

Consider the curve CC given in polar coordinates by

r=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 $C$ in the $xy$–coordinate plane.

Let aa be the value obtained in part (1). Express the answer from part (2) in the form

b+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, compute

abcπ.\frac{abc}{\pi}.

\

Ground Truth
-18
Execution Trace
Reasoning Process

[THOUGHT] I will:

  1. Use the polar area formula a=1202πr2dθa = \frac12 \int_0^{2\pi} r^2 \, d\theta with r=2+cosθr = 2+\cos\theta.
  2. Use the polar slope formula dydx=rsinθ+rcosθrcosθrsinθ\frac{dy}{dx} = \frac{r' \sin\theta + r\cos\theta}{r' \cos\theta - r\sin\theta} and evaluate at θ=π4\theta = \frac{\pi}{4}, where r=4+22r = \frac{4+\sqrt2}{2}.
  3. Simplify the slope into the form b+cb + \sqrt{c} and read off integers b,cb,c.
  4. Compute abcπ\frac{abc}{\pi} using the area aa 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=9π2a = \frac{9\pi}{2}, slope =2+2= -2 + \sqrt{2}, so b=2b=-2 and c=2c=2. Then

abcπ=(9π2)(2)(2)π=18.\frac{abc}{\pi} = \frac{\left(\frac{9\pi}{2}\right)(-2)(2)}{\pi} = -18.

[/THOUGHT] 18\boxed{-18}

Final Model Output
-18

Comparative Analysis (P0) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
316.3
K-EXAONE-236B-A23B
234.2
Deepseek-V3.2
81.3
Kanana-2-30B-Thinking
70.7
Kanana-2-30B-Thinking-2601
59.2
Llama-VARCO-8B-Instruct
49.3
GPT-5.1 (high)
38.4
HCX-007(high)
36.4
GPT-5.2 (high)
33.6
Solar-Pro-2 (31B)(high)
30.2
K-EXAONE-236B-A23B
21.4
Grok-4.1-fast
21.1
Claude-Opus-4.5
18.0
Solar-Open-100B
17.0
A.X-4.0 (72B)
16.6
EXAONE-4.0.1-32B (high)
6.7

Avg Token Usage

K-EXAONE-236B-A23B
22,901
Gemini-3-Pro-Preview
12,238
Kanana-2-30B-Thinking-2601
12,235
Kanana-2-30B-Thinking
12,196
Deepseek-V3.2
7,244
GPT-5.2 (high)
7,100
Solar-Pro-2 (31B)(high)
6,632
K-EXAONE-236B-A23B
6,596
HCX-007(high)
6,397
Grok-4.1-fast
6,290
Solar-Open-100B
5,244
GPT-5.1 (high)
4,822
Claude-Opus-4.5
4,528
Llama-VARCO-8B-Instruct
4,316
EXAONE-4.0.1-32B (high)
4,306
A.X-4.0 (72B)
3,605