Math Problem Statement

z2 = 3pie over 4. z2 = t+8i, find t

Solution

To solve for tt, we need to equate the given complex number form with the expression for z2z_2.

We are given: z2=3π4andz2=t+8iz_2 = \frac{3\pi}{4} \quad \text{and} \quad z_2 = t + 8i

So, we know that the complex number in polar form z2=3π4z_2 = \frac{3\pi}{4} corresponds to an angle of 3π4\frac{3\pi}{4} in the complex plane, and we need to express this in rectangular form (i.e., t+8it + 8i).

For z2=r(cosθ+isinθ)z_2 = r(\cos \theta + i \sin \theta), we need to identify the real and imaginary components. Here, the modulus rr is not given explicitly, but we can deduce it from the imaginary part (8i). The imaginary part is given as 8i8i, so the modulus is r=8r = 8.

Thus, we can express z2z_2 as: z2=8(cos3π4+isin3π4)z_2 = 8\left( \cos\frac{3\pi}{4} + i \sin\frac{3\pi}{4} \right)

Evaluating the trigonometric values: cos3π4=12,sin3π4=12\cos\frac{3\pi}{4} = -\frac{1}{\sqrt{2}}, \quad \sin\frac{3\pi}{4} = \frac{1}{\sqrt{2}}

So: z2=8(12+i12)z_2 = 8\left( -\frac{1}{\sqrt{2}} + i \frac{1}{\sqrt{2}} \right)

Now, compare this with z2=t+8iz_2 = t + 8i: t+8i=812+8i12t + 8i = -8 \frac{1}{\sqrt{2}} + 8i \frac{1}{\sqrt{2}}

Thus, the real part tt is: t=812=82=42t = -8 \frac{1}{\sqrt{2}} = -\frac{8}{\sqrt{2}} = -4\sqrt{2}

So, the value of tt is 42-4\sqrt{2}.

Would you like further details on this?

Here are some related questions to delve into:

  1. How to convert between polar and rectangular forms of complex numbers?
  2. What does the modulus of a complex number represent geometrically?
  3. How to find the argument of a complex number in polar form?
  4. How to graph a complex number in the complex plane?
  5. What are the properties of complex conjugates?

Tip: To avoid confusion, always write down both real and imaginary parts when working with complex numbers in rectangular form!

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar and Rectangular Forms
Trigonometry

Formulas

z = r(cos(θ) + i sin(θ))
Real part: t = r * cos(θ)
Imaginary part: Im = r * sin(θ)

Theorems

Euler's Formula
Pythagorean Identity

Suitable Grade Level

Grades 10-12