How do you find abs( 2 + 8i )? Precalculus Complex Numbers in Trigonometric Form Complex Number Plane 1 Answer Alan P. Apr 9, 2016 abs(2+8i) = 2sqrt(17) Explanation: In general abs(a+bi) = sqrt(a^2+b^2) So color(white)("XXX")abs(2+8i) = sqrt(2^2+8^2) = sqrt(68)=2sqrt(17) 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 1833 views around the world You can reuse this answer Creative Commons License