Let vector (a,b) and vector (c) be three unit vectors such that vector |a-b|^2 + |a+2c|^2 = 8

Question

Let vector (a,b) and vector (c) be three unit vectors such that vector |a-b|² + |a - c|² = 8

Then vector |a+2b|² + vector |a+2c|²is eqal to ......

Answer 1

vector |a| = |b| = |c| = 1