How do you find #abs(3+4i)#? Precalculus Complex Numbers in Trigonometric Form Complex Number Plane 1 Answer georgef Oct 27, 2016 The modulus #|a+bi|# is #sqrt (a^2+b^2)# Explanation: In this case #a=3, b=4#, so the modulus #|3+4i|# is: #sqrt (3^2+4^2)= sqrt (9+16)=sqrt(25)=5# Answer link Related questions What is the complex number plane? Which vectors define the complex number plane? What is the modulus of a complex number? How do I graph the complex number #3+4i# in the complex plane? How do I graph the complex number #2-3i# in the complex plane? How do I graph the complex number #-4+2i# in the complex plane? How do I graph the number 3 in the complex number plane? How do I graph the number #4i# in the complex number plane? How do I use graphing in the complex plane to add #2+4i# and #5+3i#? How do I use graphing in the complex plane to subtract #3+4i# from #-2+2i#? See all questions in Complex Number Plane Impact of this question 1564 views around the world You can reuse this answer Creative Commons License