How do you find #abs(4 + 5i)#? Precalculus Complex Numbers in Trigonometric Form Complex Number Plane 1 Answer sente Apr 9, 2016 #|4+5i| = sqrt(41)# Explanation: Given a complex number #a+bi#, we define the modulus of the number, denoted #|a+bi|# as #|a+bi| = sqrt(a^2+b^2)# In this case, that gives us #|4+5i| = sqrt(4^2+5^2) = sqrt(41)# 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 4341 views around the world You can reuse this answer Creative Commons License