圓心及半徑
圓方程的形式為 x² + y² + Dx + Ey + F = 0
| K | ( | K | - | 1 | ) | √ | ( |
| D | x² | + | A | x² | - | 4 | B |
| ) | ÷ | 4 | - | ( | K | x² | - |
| 3 | K | + | 2 | ) | D | ÷ | 4 |
| + | K | ( | K | - | 2 | ) | A |
| ÷ | 2 | - | K | - | 1 | + | ( |
| K | + | 1 | STO F1 或 F2 | ||||
例題: 求圓的圓心及半徑: x² + y²
- 4x + 6y - 12 = 0。
按 2ndF DEL (必要) 再按 RCL F1 ALGB 4 +/- = 6 = 12 +/- = (顯示2)
= (顯示-3，即圓心為(2,-3)) = (顯示圓的半徑為5)
相關資料:
圓心及半徑求圓方程 (Equation of circle by centre and radius)
直徑兩點求圓方程 (Equation of circle by 2 end-point of diameter)
已知斜率求圓的切線 (Tangent to Circle with given slope)
外點至圓的切線斜率 (Slope of tangent to circle from external point)
直線與圓形的交點 (Intersection points of line and circle)
三點求圓方程 (應用內置聯立三元一次方程 ) (Equation of circle from three points)