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Complex Analysis - Maths KU

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408 Chapter 7 Conformal Mappings<br />

Now from (12) of Theorem 7.4 with w1 =1,w2 = i, and w3 = −1, the desired<br />

mapping w = T (z) must satisfy<br />

z + i<br />

1+i<br />

w − 1 i +1<br />

=<br />

w +1i<br />

− 1 .<br />

After solving for w and simplifying we obtain<br />

w = T (z) =<br />

z +1<br />

−z +1− 2i .<br />

EXERCISES 7.2 Answers to selected odd-numbered problems begin on page ANS-22.<br />

In Problems 1–4, find the images of the points 0, 1, i, and ∞ under the given linear<br />

fractional transformation T .<br />

1. T (z) = i<br />

z<br />

3. T (z) =<br />

z + i<br />

z − i<br />

2. T (z) = 2<br />

z − i<br />

4. T (z) =<br />

z − 1<br />

z<br />

In Problems 5–8, find the image of the disks |z| ≤1 and |z − i| ≤1 under the given<br />

linear fractional transformation T .<br />

5. T is the mapping in Problem 1 6. T is the mapping in Problem 2<br />

7. T is the mapping in Problem 3 8. T is the mapping in Problem 4<br />

In Problems 9–12, find the image of the half-planes x ≥ 0 and y ≤ 1 under the given<br />

linear fractional transformation T .<br />

9. T is the mapping in Problem 1 10. T is the mapping in Problem 2<br />

11. T is the mapping in Problem 3 12. T is the mapping in Problem 4<br />

In Problems 13–16, find the image of the region shown in color under the given<br />

linear fractional transformation.<br />

13. T (z) = z<br />

z − 2<br />

y<br />

Figure 7.15 Figure for Problem 13<br />

1<br />

x<br />

14. T (z) =<br />

z − i<br />

z +1<br />

y<br />

Figure 7.16 Figure for Problem 14<br />

1<br />

x

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