In Exercises 53–58, perform the indicated operation(s) and write the result in standard form. ___ ___ 5√(−16) + 3√(−81)
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
11. Graphing Complex Numbers
Products and Quotients of Complex Numbers
Multiple Choice
Given z1=32(cos25°+isin25°) and z2=25(cos15°+isin15°), find the product z1・z2.
A
z1・z2=35CiS(375°)
B
z1⋅z2=35CiS(40°)
C
z1・z2=619CiS(40°)
D
z1・z2=619CiS(375°)
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Verified step by step guidance1
Identify the given complex numbers in polar form: z1 = \(\frac{2}{3}\)(\(\cos\) 25\(\degree\) + i\(\sin\) 25\(\degree\)) and z2 = \(\frac{5}{2}\)(\(\cos\) 15\(\degree\) + i\(\sin\) 15\(\degree\)).
Recall the formula for multiplying two complex numbers in polar form: If z1 = r1(CiS θ1) and z2 = r2(CiS θ2), then z1 \(\cdot\) z2 = r1 \(\cdot\) r2 \(\cdot\) CiS(θ1 + θ2).
Calculate the product of the magnitudes: \(\frac{2}{3}\) \(\cdot\) \(\frac{5}{2}\) = \(\frac{10}{6}\) = \(\frac{5}{3}\).
Add the angles of the complex numbers: 25\(\degree\) + 15\(\degree\) = 40\(\degree\).
Combine the results to express the product in polar form: z1 \(\cdot\) z2 = \(\frac{5}{3}\)CiS(40\(\degree\)).
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