Chaining a real product into a real polar conversion
Multiplying (3+4i) by (1+2i) gives a real result of −5 + 10i. Feeding that exact real and imaginary part into the polar form calculator finds a magnitude of 11.18033989 and an angle of 116.56505118° — the polar description of the product, computed as a genuine second step from the first calculator's real output.
Why this two-step process is a normal part of working with complex numbers
Complex number arithmetic (addition, subtraction, multiplication, division) is naturally done in rectangular form, since that's how the operations are defined — but the result often needs converting to polar form afterward for interpretation, comparison, or further multiplication, since polar form makes those operations simpler.
What the resulting angle actually represents
116.57° places the product in the second quadrant (positive imaginary, negative real) — consistent with the product's real part being negative (−5) and imaginary part being positive (10). The polar angle directly encodes which quadrant a complex number sits in, information that isn't as immediately visible from the rectangular real/imaginary pair alone.
A general pattern worth recognizing
Any calculator whose output happens to be a real and imaginary pair — whether from addition, multiplication, or another operation — can be fed directly into the polar form calculator the same way, since polar conversion only needs those two numbers regardless of how they were produced.