My 8th grader made this error on tonight
Question
My 8th grader made this error on tonight's geometry homework:
- Problem: ight triangle with one leg a = 6 and hypotenuse c = 10. Find the length of unknown leg b.
- What she wrote: b^2 = 6^2 + 10^2 = 36 + 100 = 136, so b = sqrt(136).
- Correct repair: Identify hypotenuse is 10: b^2 = 10^2 - 6^2 = 100 - 36 = 64, so b = 8.
- Tag: pythagorean-hypotenuse
- Cause: Added squares of given numbers instead of subtracting leg from hypotenuse.
Please record this 5-line card into our mistake notebook and set a daily review reminder at 19:00 (America/New_York).
Do not teach a long geometry lesson; just file the card and confirm the five lines.
Answer
I'll file this card and set the reminder. Let me first check today's date in your timezone and read the family profile.
In your timezone it's 2026-09-19. Filing the card now.
Card filed.
Card filed — id `80b4970b28cb1d13`, tag `pythagorean-hypotenuse`.
The five lines that went into your personal notebook:
| 行 | 内容 |
|---|---|
| 题面 | ight triangle, leg a = 6, hypotenuse c = 10. Find b. |
| 错法 | b² = 6² + 10² = 36 + 100 = 136, so b = √136. |
| 修法 | Identify hypotenuse is 10: b² = 10² − 6² = 100 − 36 = 64, so b = 8. |
| tag | pythagorean-hypotenuse |
| 错因 | Added squares of given numbers instead of subtracting leg from hypotenuse. |
eminder — daily review at 19:00 America/New_York is already on (schedule id `a33d98ab-ed55-4232-bd17-96136c20af11`); system nudged it to 19:11:11 to avoid a hot slot. First run tonight NY time.
First due check lands on 2026-09-20 (tomorrow, day 1 of the [1, 3, 7, 14, 30] ladder). When it fires, she'll be asked the prompt first — no answer key shown — and the repair line is reserved for after she answers.
Say "停掉该定时" any time to disable it.