+79
If possible please show me how you did it. I do not understand how to do these problems.
Edited to present one question only - Melody.
+9519 c + di lies on the 1st Quadrant, which means the polar form of c + di is \(re^{i\theta}\), where \(r = \sqrt{c^2 + d^2}\), \(\theta \in \left(0, \dfrac\pi2\right) \).
e - fi lies on the 4th Quadrant, which means the polar form of e - fi is \(Re^{i\phi}\), where \(R = \sqrt{e^2 + f^2}\), \(\phi \in \left(\dfrac{3\pi}2, 2\pi\right) \)
Therefore, (c + di)(e - fi) = \(rRe^{i\left(\theta + \phi\right)}\)
For \(\theta \in \left(0, \dfrac\pi2\right) \) and \(\phi \in \left(\dfrac{3\pi}2, 2\pi\right) \), \(\theta + \phi \in \left(\dfrac{3\pi}{2} , \dfrac{5\pi}{2}\right)\)
Therefore (c + di)(e - fi) can lie inside the 4th Quadrant and the 1st Quadrant.
