Skip to content
CalcGospel 國際數學圖譜
返回

CIE 9709 2023 June Paper 33 Q3

A Level / CIE / P3

CIE 9709 2023 June Paper 33 Paper · Question 3

题目

Problem

On a sketch of an Argand diagram, shade the region whose points represent complex numbers zz satisfying the inequalities ∣z−3−i∣≤3|z-3-\mathrm{i}|\le3 and ∣z∣≥∣z−4i∣|z|\ge|z-4\mathrm{i}|.

(4)
题目中文翻译

在阿尔冈图的草图上,用阴影表示由满足不等式 ∣z−3−i∣≤3|z-3-\mathrm{i}|\le3 和 ∣z∣≥∣z−4i∣|z|\ge|z-4\mathrm{i}| 的复数 zz 所对应的点组成的区域。

(4)
原卷通用作答要求

Answer all questions. You should use a calculator where appropriate.

You must show all necessary working clearly; no marks will be given for unsupported answers from a calculator.

Give non-exact numerical answers correct to 3 significant figures, or 1 decimal place for angles in degrees, unless a different level of accuracy is specified in the question.

请回答所有题目。适当时应使用计算器。必须清楚展示所有必要的计算过程;仅给出计算器答案而没有过程,不予评分。除非题目另有精度要求,非精确数值答案保留 3 位有效数字,以度为单位的角度保留 1 位小数。

解答

解法一

思路

展开

模条件给出闭圆盘。另一个距离条件比较到 (0,0)(0,0) 与 (0,4)(0,4) 的距离,边界是水平垂直平分线 y=2y=2,取上方。

答题过程

展开

Write z=x+yiz=x+y\mathrm{i}. The first condition is

(x−3)2+(y−1)2≤9,(x-3)^2+(y-1)^2\le9,

the closed disc with centre (3,1)(3,1) and radius 33.

The second condition gives

x2+y2≥x2+(y−4)2.x^2+y^2\ge x^2+(y-4)^2.

Thus 8y≥168y\ge16, or y≥2y\ge2.

Draw the circle and the horizontal line y=2y=2, then shade the part inside the circle and on or above the line, including the boundaries.