Question

(vektor math kelas 12) diketahui |a+b| = 10 dan |a-b| = 6, maka a.b =

Answer 1

Verified answer

Vektor
kelas X

|a+b| = |a|² + |b|² + 2|a|.|b|.cosα

|a-b| = |a|² + |b|² - 2|a|.|b|.cosα

a.b = |a| |b| cos α

100 = |a|² + |b|² + 2|a|.|b|.cosα
36= |a|² + |b|² - 2|a|.|b|.cosα
_________________________ -
64 = 4 |a| |b| cos α
a.b = |a| |b| cos α = 16