c. Multiply and Divide in Modulus-Argument Form

From the DfE Mathematics AS and A-Level Further Maths Content (LINK):

Multiplying and Dividing in Modulus-Argument Form

B6-01 Complex Numbers: Multiplying Complex Numbers Investigation

B6-02 Complex Numbers: Multiplying Complex Numbers in Modulus-Argument Form

B6-03 Complex Numbers: Proof of Multiplying Complex Numbers

B6-04 Complex Numbers: Deriving a Similar Result for Division