Difference between revisions of "Talk:2024 AMC 12B Problems/Problem 12"

(Created page with "The quadrilateral can be broken down into two triangles: one between z and z^2 and the other between z^2 and z^3. Since the angle between each complex number is the same by De...")
 
Line 1: Line 1:
The quadrilateral can be broken down into two triangles: one between z and z^2 and the other between z^2 and z^3. Since the angle between each complex number is the same by De Moivre's Theorem, the area of these triangles is 1/2 2 * 4 sin(theta) and 1/2 4 * 8 sin(theta). Thus, 1/2 2 * 4 sin(theta) + 1/2 4 * 8 sin(theta) = 15, and sin(theta) = 15/20 = 3/4. Since the imaginary part of z is equal to |z|sin(theta), the imaginary part = 2 * 3/4 = 3/2.
+
The quadrilateral can be broken down into two triangles: one between z and z^2 and the other between z^2 and z^3. Since the angle between each complex number is the same by De Moivre's Theorem, the area of these triangles is 1/2 2 * 4 sin(theta) and 1/2 4 * 8 sin(theta). Thus, 1/2 2 * 4 sin(theta) + 1/2 4 * 8 sin(\theta) = 15, and sin(theta) = 15/20 = 3/4. Since the imaginary part of z is equal to |z|sin(theta), the imaginary part = 2 * 3/4 = 3/2.

Revision as of 19:56, 14 November 2024

The quadrilateral can be broken down into two triangles: one between z and z^2 and the other between z^2 and z^3. Since the angle between each complex number is the same by De Moivre's Theorem, the area of these triangles is 1/2 2 * 4 sin(theta) and 1/2 4 * 8 sin(theta). Thus, 1/2 2 * 4 sin(theta) + 1/2 4 * 8 sin(\theta) = 15, and sin(theta) = 15/20 = 3/4. Since the imaginary part of z is equal to |z|sin(theta), the imaginary part = 2 * 3/4 = 3/2.