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Q. 39

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Precalculus Enhanced with Graphing Utilities
Found in: Page 592
Precalculus Enhanced with Graphing Utilities

Precalculus Enhanced with Graphing Utilities

Book edition 6th
Author(s) Sullivan
Pages 1200 pages
ISBN 9780321795465

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Short Answer

Find zw and zw. Leave the answers in polar form.

role="math" localid="1646661399572" z=2+2iw=3-i

zw in polar form is 42cos 15°+isin 15°.

zw in polar form is 2cos 75°+isin 75°.

See the step by step solution

Step by Step Solution

Step 1. Given information.

Consider the given question,

z=2+2iw=3-i

The multiplication of the polar form of complex numbers is given by,

z1z2=r1r2cosθ1+θ2+isinθ1+θ2 ...... (i)z1z2=r1r2cosθ1-θ2+isinθ1-θ2 ...... (ii)

We need to write the given numbers in polar form.

r=x2+y2,θ=tan-1yx

Step 2. Find the polar form of w.

Determine the polar form of z,

rz=22+22rz=22θz=tan-122θz=45°

Therefore, z=22cos 45°+isin45°.

Determine the polar form of w,

rw=32+-12rw=2θw=tan-1-13θw=-30°

Therefore, w=2cos-30°+isin-30°

Step 3. Find zw and zw.

Substitute the values of z,w in equation (i),

z·w=22cos45°+isin45°·2cos-30°+isin-30°z·w=222cos45°+-30°+isin45°+-30°z·w=42cos 15°+isin 15°

Substitute the values of z,w in equation (ii),

zw=22cos45°+isin 45°2cos-30°+isin-30°zw=222cos45°--30°+isin45°--30°zw=2cos 75°+isin 75°

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