the impedance of a circuit can be calculated by the expression
Z = Z1 X Z2 / Z1 + Z2
If Z1 = 4 + j10 & Z2 = 12 - j3
how do I calculate the impedance Z in rectangular and polar forms?


First, we need to know what the formula really is. Is it
which is what you wrote, or is it
?
With Z1= 4+ j10, Z2= 12- j3, Z1+ Z2= 16+ j7. Now, write the three numbers, 4+j10, 12- j3, and 16+ j7 in polar form: for 4+ j10,and [itex]\theta= arctan(10/4)= arctan(5/2)= 1.19.
Multiplyingand
gives
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