# Amateur Extra Lesson 4.1, Radio Mathematics, 11th Edition

Here’s your video introduction to Section 4.1, “Radio Mathematics,” in the 11th edition of the ARRL Extra Class License Manual for Ham Radio. This section delves into rectangular and polar coordinates, and complex coordinates. The material in this section lays the groundwork to understand how reactances and resistances combine in amateur radio.

You can find a complete list of the Amateur Extra videos by clicking here, or click here to go to the YouTube Amateur Extra playlist. Please post your questions either below or on the YouTube page for this video. Good luck in your studies!

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### 3 Responses to Amateur Extra Lesson 4.1, Radio Mathematics, 11th Edition

1. David Casler says:

Take a closer look and keep track of the j’s. The chart demonstrates polynomial multiplication. Note that j^2 is -1.

2. Sylvia Stephens says:

I am trying wrap my mind around your math problem. I am ok up to
24 + j14-j2 24. the next line is 24+j14+24. What happened??? Is it because you have a -j24 as an answer, that you drop the- j??

3. Glen says:

Thank You so very much!

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