panjang vektor a=4√6,a.b=8 dan sudut antara vektor a dan b=45° maka panjang vektor

Dik:
• |a| = 4√6
• a x b = 8
• <¢ = 45°
Dit: |b|..?
penyelesaian:
=> a x b = |a| x |b| cos ¢
=> 8 = 4√6 x |b| x 1/2√2
=> 8 = 4√6 x 1/2√2 x |b|
=> 8 = 2√12 x |b|
=> 8 = 4√3 x |b|
=> |b| = 8 / 4√3
=> |b| = 2√3