Problem Analysis #21

56.55s
9,571 toks
Problem Statement

\text{Let } P_1(1+\cos t,; \sin t)\text{ be a point moving on the circle with center } (1,0)\text{ and radius } 1,]and P2(2cosθ(t),  2sinθ(t)) be a point moving on the circle with center (0,0) and radius 2.\text{and }P_2(2\cos\theta(t),\; 2\sin\theta(t))\text{ be a point moving on the circle with center } (0,0)\text{ and radius } 2.Both points start at the intersection point (2,0)(2,0) of the two circlesand move counterclockwise along their respective circles.Assume that their speeds satisfyP1(t):P2(t)=1:4,(0t2π).|P_1'(t)| : |P_2'(t)| = 1 : 4,\qquad (0 \le t \le 2\pi).Let t=t0t = t_0 be the time when the distance between P1P_1 and P2P_2 is maximized.At this moment, the following expression:sint2sinθ(t)    (1+cost)2cosθ(t)=pq,\sin t \cdot 2\sin\theta(t)\;-\;(1+\cos t)\cdot 2\cos\theta(t)=\frac{p}{q},where pp and qq are relatively prime positive integers.Find the value of p+qp + q.oindent

Ground Truth
141
Execution Trace
Reasoning Process

[THOUGHT] To solve the problem, we start by determining the parametric equations for the positions of ( P_1 ) and ( P_2 ). Given the speed ratio ( |P_1'(t)| : |P_2'(t)| = 1 : 4 ), we find that ( \theta(t) = 2t ) for ( P_2 ). The distance squared between ( P_1 ) and ( P_2 ) is derived and simplified to a quadratic function in ( \cos t ). The maximum distance occurs when ( \cos t = -\frac{1}{8} ). Using this value, we compute the required trigonometric expression involving ( \sin t ), ( \cos t ), ( \sin \theta(t) ), and ( \cos \theta(t) ) at ( t = t_0 ). The expression simplifies to ( \frac{77}{64} ), leading to ( p + q = 141 ).

[PYTHON] import math from sympy import symbols, solve, cos, sin, simplify

Define symbols

t = symbols('t') u = cos(t)

Distance squared simplified to quadratic in u

D_squared = -8u**2 - 2u + 10

Find u that maximizes D_squared (vertex of parabola)

u_max = solve(D_squared.diff(u), u)[0] u_val = u_max.evalf() # Should be -1/8

Calculate sin(t) when cos(t) = -1/8

sin_t = sqrt(1 - u_val**2) sin_t = sin_t.evalf()

Calculate theta(t) = 2t, so cos(theta) and sin(theta)

cos_theta = 2u_val**2 - 1 sin_theta = 2sin_t*u_val

Compute the expression: sin(t)2sin(theta) - (1 + cos(t))2cos(theta)

expression = sin_t * 2 * sin_theta - (1 + u_val) * 2 * cos_theta expression_simplified = simplify(expression)

Since we know the exact value should be 77/64, verify with exact fractions

u_exact = -1/8 sin_t_exact = sqrt(1 - u_exact2) cos_theta_exact = 2*u_exact2 - 1 sin_theta_exact = 2sin_t_exactu_exact expression_exact = sin_t_exact * 2 * sin_theta_exact - (1 + u_exact) * 2 * cos_theta_exact numerator = expression_exact.as_numer_denom()[0] denominator = expression_exact.as_numer_denom()[1] p_plus_q = numerator + denominator

print(p_plus_q) [/PYTHON]

Tool Output
[PYTHON OUTPUT] ValueError: Can't calculate derivative wrt cos(t). [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The error in the Python code was due to an incorrect derivative approach. Manually solving, the maximum distance occurs at ( \cos t = -\frac{1}{8} ). Calculating the expression with ( \sin t = \frac{3\sqrt{7}}{8} ), ( \cos \theta = -\frac{15}{16} ), and ( \sin \theta = -\frac{3\sqrt{7}}{32} ), the expression simplifies to ( \frac{147}{128} ). Thus, ( p + q = 147 + 128 = 275 ).

\boxed{275}

Final Model Output
275

Comparative Analysis (P21) (Average across runs)

Avg Time Taken

Llama-VARCO-8B-Instruct
93.9
Gemini-3-Pro-Preview
90.3
GPT-5.1 (high)
73.6
Deepseek-V3.2
67.4
Solar-Pro-2 (31B)(high)
56.5
Grok-4.1-fast
41.6
HCX-007(high)
35.9
A.X-4.0 (72B)
32.7
Claude-Opus-4.5
28.3
EXAONE-4.0.1-32B (high)
9.6

Avg Token Usage

GPT-5.1 (high)
12127.0
Gemini-3-Pro-Preview
10461.0
Grok-4.1-fast
10394.0
Solar-Pro-2 (31B)(high)
9571.0
Deepseek-V3.2
5739.0
A.X-4.0 (72B)
5617.0
EXAONE-4.0.1-32B (high)
5381.0
Claude-Opus-4.5
5284.0
HCX-007(high)
4768.0
Llama-VARCO-8B-Instruct
3110.0