Photo AI

Let $ z = 1 - ext{i}oldsymbol{ oot{3}} $ and $ w = 1 + ext{i} $ - HSC - SSCE Mathematics Extension 2 - Question 11 - 2017 - Paper 1

Question icon

Question 11

Let-$-z-=-1----ext{i}oldsymbol{-oot{3}}-$-and-$-w-=-1-+--ext{i}-$-HSC-SSCE Mathematics Extension 2-Question 11-2017-Paper 1.png

Let $ z = 1 - ext{i}oldsymbol{ oot{3}} $ and $ w = 1 + ext{i} $. (i) Find the exact value of the argument of $ z $. (ii) Find the exact value of the argumen... show full transcript

Worked Solution & Example Answer:Let $ z = 1 - ext{i}oldsymbol{ oot{3}} $ and $ w = 1 + ext{i} $ - HSC - SSCE Mathematics Extension 2 - Question 11 - 2017 - Paper 1

Step 1

(i) Find the exact value of the argument of $ z $

96%

114 rated

Answer

To find the argument of zz, we first express z=1exti3z = 1 - ext{i}\sqrt{3} in polar form. The modulus of zz is given by:

z=(1)2+(3)2=4=2.|z| = \sqrt{(1)^2 + (\sqrt{3})^2} = \sqrt{4} = 2.

The argument of zz, denoted as ( \text{arg}(z) ), can be computed using the formula:

arg(z)=tan1(Im(z)Re(z))=tan1(31).\text{arg}(z) = \tan^{-1}\left(\frac{\text{Im}(z)}{\text{Re}(z)}\right) = \tan^{-1}\left(-\frac{\sqrt{3}}{1}\right).

Since zz lies in the fourth quadrant, we adjust the angle:

arg(z)=π3.\text{arg}(z) = -\frac{\pi}{3}.

Step 2

(ii) Find the exact value of the argument of $ \frac{z}{w} $

99%

104 rated

Answer

To find the argument of zw\frac{z}{w}, we compute:

arg(zw)=arg(z)arg(w).\text{arg}\left(\frac{z}{w}\right) = \text{arg}(z) - \text{arg}(w).

From part (i), we already found ( \text{arg}(z) = -\frac{\pi}{3} ). Now, we calculate ( \text{arg}(w) ):

w=1+i    arg(w)=tan1(11)=π4.w = 1 + \text{i} \implies \text{arg}(w) = \tan^{-1}\left(\frac{1}{1}\right) = \frac{\pi}{4}.

Now substitute the values:

arg(zw)=π3π4=4π+3π12=7π12.\text{arg}\left(\frac{z}{w}\right) = -\frac{\pi}{3} - \frac{\pi}{4} = -\frac{4\pi + 3\pi}{12} = -\frac{7\pi}{12}.

Step 3

Find the value of $ \alpha $

96%

101 rated

Answer

For the hyperbola given by ( \frac{x^2}{12} - \frac{y^2}{4} = 1 ), the asymptotes are given by:

x212y24=0    y24=x212    y=±23x.\frac{x^2}{12} - \frac{y^2}{4} = 0 \implies \frac{y^2}{4} = \frac{x^2}{12} \implies y = \pm \frac{2}{\sqrt{3}}x.

The slope of the asymptote is given by:

m=23.m = \frac{2}{\sqrt{3}}.

To find the angle ( \alpha ) with the positive x-axis, we use:

tan(α)=m=23.\tan(\alpha) = m = \frac{2}{\sqrt{3}}.

Thus, we have:

α=tan1(23)=π6.\alpha = \tan^{-1}(\frac{2}{\sqrt{3}}) = \frac{\pi}{6}.

Step 4

Sketch the region in the Argand diagram

98%

120 rated

Answer

To sketch the region defined by the inequalities:

  1. π4argz0-\frac{\pi}{4} \leq \text{arg} z \leq 0 creates a sector in the Argand plane covering the angles from π4-\frac{\pi}{4} to 00. This is the right side of the negative x-axis.
  2. The inequality z(1+i)1|z - (-1 + \text{i})| \leq 1 represents a circle centered at (1,1)(-1, 1) with a radius of 1.

We combine these two regions: the sector from π4-\frac{\pi}{4} to 00 intersected with the area inside the circle leads to a shaded region in the Argand diagram.

Join the SSCE students using SimpleStudy...

97% of Students

Report Improved Results

98% of Students

Recommend to friends

100,000+

Students Supported

1 Million+

Questions answered

;