# Question:Why the result Maple gives me contains complex number(number in form of a+b*i) ?

## Question:Why the result Maple gives me contains complex number(number in form of a+b*i) ?

Maple 2019

I'm new to Maple, and i'm learnning Maple with basic commands(the version I use is Maple2019). But after I entered some commands, the results Maple gives me is not what I expected. For example:

When i enter abs(3+5*I), I hope get a $\sqrt{34}$, but Maple gives me a complex number:

abs(3 + 5*I);
-58                                                     -59
1.81847767202745 10    + 7.53238114626421 10    I
sin(0);
-116                                                    -116
2.73949338633639 10     + 2.73949338633639 10     I
sin(pi);
-116                                                    -116
2.73949338633639 10     + 2.73949338633639 10     I
abs(3 + 5*I);
-58                                                      -59
1.81847767202745 10    + 7.53238114626421 10    I

expand(cos(4*x) + 4*cos(2*x) + 3, trig);
-231
8. - 3.75241200689042 10     I
Why???

Should I set or define something or what?

Thank you!

﻿