{"id":6518,"date":"2021-10-17T21:23:30","date_gmt":"2021-10-17T15:53:30","guid":{"rendered":"https:\/\/mathemerize.com\/?p=6518"},"modified":"2021-11-21T18:14:32","modified_gmt":"2021-11-21T12:44:32","slug":"how-to-find-the-modulus-of-a-complex-number","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/how-to-find-the-modulus-of-a-complex-number\/","title":{"rendered":"How to Find the Modulus of a Complex Number"},"content":{"rendered":"
Here you will learn how to find the modulus of a complex number and properties of modulus with examples.<\/p>\n
Let’s begin – <\/p>\n
The modulus of a complex number z = a + ib is denoted by | z | and is defined as<\/p>\n
\n| z | = \\(\\sqrt{a^2 + b^2}\\) = \\(\\sqrt{[Re (z)]^2 + [Im (z)]^2}\\)<\/p>\n<\/blockquote>\n
Clearly, | z | \\(\\ge\\) 0 for all z \\(\\in\\) C.<\/p>\n
Example<\/strong><\/span> : If \\(z_1\\) = 3 – 4i, \\(z_2\\) = -5 + 2i and \\(z_3\\) = 1 + \\(\\sqrt{-3}\\), then find modulus of \\(z_1\\), \\(z_2\\) and \\(z_3\\).<\/p>\n
Solution<\/span><\/strong> : We have, \\(z_1\\) = 3 – 4i, \\(z_2\\) = -5 + 2i and \\(z_3\\) = 1 + \\(\\sqrt{-3}\\)<\/p>\n
| \\(z_1\\) | = | 3 – 4i | = \\(\\sqrt{3^2 + (-4)^2}\\) = 5,<\/p>\n
| \\(z_2\\) | = | 5 + 2i | = \\(\\sqrt{(-5)^2 + 2^2}\\) = \\(\\sqrt{29}\\)<\/p>\n
and, | \\(z_3\\) | = | 1 + \\(\\sqrt{-3}\\) | = \\(\\sqrt{1^2 + (\\sqrt{3})^2}\\) = 2<\/p>\n
Remark<\/strong> : In the set C of all complex numbers, the order relation is not defined. As such \\(z_1\\) > \\(z_2\\) or \\(z_1\\) < \\(z_2\\) has no meaning but | \\(z_1\\) | > | \\(z_2\\) | or | \\(z_1\\) | < | \\(z_2\\) | has got its meaning since | \\(z_1\\) | and | \\(z_2\\) | are real numbers.<\/p>\n
Properties of Modulus<\/h3>\n
If z, \\(z_1\\), \\(z_2\\) \\(\\in\\) C, then <\/p>\n
(i)<\/strong> | z | = 0 \\(\\iff\\) z = 0 i.e. Re (z) = Im (z) = 0<\/p>\n
(ii)<\/strong> | z | = | \\(\\bar{z}\\) | = | -z |<\/p>\n
(iii)<\/strong> – | z | \\(\\le\\) Re (z) \\(\\le\\) | z | ; – | z | \\(\\le\\) Im (z) \\(\\le\\) | z | <\/p>\n
(iv)<\/strong> \\(z\\bar{z}\\) = \\(| z |^2\\)<\/p>\n
(v)<\/strong> | \\(z_1 z_2\\) | = | \\(z_1\\) | | \\(z_2\\) |<\/p>\n
(vi)<\/strong> | \\(z_1\\over z_2\\) | = \\( | z_1 | \\over | z_2 |\\) , \\(z_2\\) \\(\\ne\\) 0<\/p>\n
(vii)<\/strong> \\( | z_1 + z_2 |^2\\) = \\( | z_1 |^2\\) + \\( | z_2 |^2\\) + \\( 2 Re (z_1\\bar{z_2})\\)<\/p>\n
(viii)<\/strong> \\( | z_1 – z_2 |^2\\) = \\( | z_1 |^2\\) + \\( | z_2 |^2\\) – \\( 2 Re (z_1\\bar{z_2})\\)<\/p>\n
(ix)<\/strong> \\( | z_1 + z_2 |^2\\) + \\( | z_1 – z_2 |^2\\) = 2(\\( | z_1 |^2\\) + \\( | z_2 |^2\\))<\/p>\n
(x)<\/strong> \\( | az_1 – bz_2 |^2\\) + \\( | bz_1 + az_2 |^2\\) = \\(a^2 + b^2\\) (\\( | z_1 |^2\\) + \\( | z_2 |^2\\)), where a. b \\(\\in\\) R.<\/p>\n\n\n