Khan Academy
Khan Academy: Complex Numbers From Absolute Value & Angle
Given the absolute value and the angle of a complex number, express the number in the form a+bi. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Interactive Mathematics
Interactive Mathematics: Exponential Form of a Complex Number
Several examples are presented to demonstrate how to write complex numbers in exponential for. The demonstrations concludes with a comparison of different forms complex numbers: rectangular, exponential, and polar.