How do you find the projection of u=<4,8> onto v=<-1,2>? Precalculus Dot Product of Vectors Vector Projection 1 Answer VinÃcius Ferraz May 28, 2017 #(-12/5, 24/5)# Explanation: #u * v = ||u|| * ||v|| * cos theta# But you want #||u|| * cos theta * hat v = frac{u * v}{||v||} * frac{v}{||v||} = frac{u*v}{v*v}*v# #= frac{4(-1) + 8*2}{(-1)^2 + 2^2} * (-1, 2)# #= frac{12}{5} * (-1, 2)# Answer link Related questions What is the vector projection formula? What are vector projections used for? How does a vector differ from its projection? How do I find the orthogonal vector projection of #vec{a}# onto #vec{b}#? How do I determine the vector projection of a vector? What is vector projection? How do I find the orthogonal projection of a vector? How do I find the orthogonal projection of two vectors? How do you find the vector #C# that is perpendicular to #A-> -3x+9y-z=0# and which vector #C#... Question #8f5e6 See all questions in Vector Projection Impact of this question 2256 views around the world You can reuse this answer Creative Commons License