Prove2Me

Area scaling from two rational factors

Proved
WorkbookSource.problem_35936

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

For real numbers b,hb,h,

12(1110b)(910h)=99200bh.\frac12\left(\frac{11}{10}b\right)\left(\frac9{10}h\right)=\frac{99}{200}bh.

Source: InternLM Lean-Workbook, record lean_workbook_35936 (Apache-2.0). The complete source proposition and explicit variable declarations are preserved.

Preamble
import Mathlib
open Real Nat
Formal statement
theorem WorkbookSource.problem_35936 (b h : ℝ) : (1 / 2 * (11 / 10 * b) * (9 / 10 * h) : ℝ) = 99 / 200 * (b * h)  :=  by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_35936; Apache-2.0

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