Area calculations in complex plane

A question is this type if and only if it requires calculating the exact area of a region defined by complex loci or inequalities on an Argand diagram.

5 questions · Challenging +1.0

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Edexcel CP AS 2021 June Q5
10 marks Standard +0.8
5. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{8d7dcb9f-510c-42c7-bcac-6d6ab3ed6468-12_584_830_246_639} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} Figure 1 shows an Argand diagram.
The set \(P\), of points that lie within the shaded region including its boundaries, is defined by $$P = \{ z \in \mathbb { C } : a \leqslant | z + b + c \mathrm { i } | \leqslant d \}$$ where \(a\), \(b\), \(c\) and \(d\) are integers.
  1. Write down the values of \(a , b , c\) and \(d\). The set \(Q\) is defined by $$Q = \{ z \in \mathbb { C } : a \leqslant | z + b + c \mathrm { i } | \leqslant d \} \cap \{ z \in \mathbb { C } : | z - \mathrm { i } | \leqslant | z - 3 \mathrm { i } | \}$$
  2. Determine the exact area of the region defined by \(Q\), giving your answer in simplest form.
Edexcel CP AS 2024 June Q5
10 marks Standard +0.8
  1. Given that on an Argand diagram the locus of points defined by \(| z + 5 - 12 i | = 10\) is a circle,
    1. write down,
      1. the coordinates of the centre of this circle,
      2. the radius of this circle.
    2. Show, by shading on an Argand diagram, the set of points defined by
    $$| z + 5 - 12 i | \leqslant 10$$
  2. For the set of points defined in part (b), determine the maximum value of \(| z |\) The set of points \(A\) is defined by $$A = \{ z : 0 \leqslant \arg ( z + 5 - 20 i ) \leqslant \pi \} \cap \{ z : | z + 5 - 12 i | \leqslant 10 \}$$
  3. Determine the area of the region defined by \(A\), giving your answer to 3 significant figures.
Edexcel CP2 2024 June Q5
9 marks Standard +0.8
  1. The locus \(C\) is given by
$$| z - 4 | = 4$$ The locus \(D\) is given by $$\arg z = \frac { \pi } { 3 }$$
  1. Sketch, on the same Argand diagram, the locus \(C\) and the locus \(D\) The set of points \(A\) is defined by $$A = \{ z \in \mathbb { C } : | z - 4 | \leqslant 4 \} \cap \left\{ z \in \mathbb { C } : 0 \leqslant \arg z \leqslant \frac { \pi } { 3 } \right\}$$
  2. Show, by shading on your Argand diagram, the set of points \(A\)
  3. Find the area of the region defined by \(A\), giving your answer in the form \(p \pi + q \sqrt { 3 }\) where \(p\) and \(q\) are constants to be determined.
Edexcel CP2 Specimen Q6
13 marks Challenging +1.8
  1. (a) (i) Show on an Argand diagram the locus of points given by the values of \(z\) satisfying
$$| z - 4 - 3 \mathbf { i } | = 5$$ Taking the initial line as the positive real axis with the pole at the origin and given that \(\theta \in [ \alpha , \alpha + \pi ]\), where \(\alpha = - \arctan \left( \frac { 4 } { 3 } \right)\),
(ii) show that this locus of points can be represented by the polar curve with equation $$r = 8 \cos \theta + 6 \sin \theta$$ The set of points \(A\) is defined by $$A = \left\{ z : 0 \leqslant \arg z \leqslant \frac { \pi } { 3 } \right\} \cap \{ z : | z - 4 - 3 \mathbf { i } | \leqslant 5 \}$$ (b) (i) Show, by shading on your Argand diagram, the set of points \(A\).
(ii) Find the exact area of the region defined by \(A\), giving your answer in simplest form.
OCR FP1 AS 2018 March Q4
6 marks Standard +0.8
4 Find, in exact form, the area of the region on an Argand diagram which represents the locus of points for which \(| z - 5 - 2 \mathrm { i } | \leqslant \sqrt { 32 }\) and \(\operatorname { Re } ( z ) \geqslant 9\).