uji kompetensi 1-
NAMA: Anggun Indah Sari DarmaYanti KELAS: X MIPA 3 ABSEN: 9 [1] [5] [4] 1. Jika vektor a= [2], b= [4] dan c=[-1] maka hasil operasi vektor a+2b-3c adalah=... [3] [ -1] [1] Diketahui a = (1 2 3) b = (5 4 –1) c = (4 –1 1) Ditanyakan Vektor a + 2b – 3c = ... ? Jawab a + 2b – 3c = = = = = (–1 13 –2) = [D] –1 + 13– 2 2. Diketahui |a|= akar 3, |b|=1 dan |a-b|=1. panjang vektor a+b adalah=... |a-b|^2 = |a|^2 + |b|^2-2.a.b cos a 1^2=[akar 3]^2-2ab cos a 1=3+1-2ab cos a 1=4-2ab cos a 2ab cos a= 4-1 2ab cos a= 3 |a+b|^2= |a|^2+|b|^2 +2ab cos a |a+b|^2 =[akar 3]^2 +1^2 +3 |a+b|^2= 3+1+3 |a+b|^2= 7 |a+b|= [C] akar 7 3. Diketahui a=2i-3j+4k dan b=5j+5k. nilai a.b adalah... a = 2i - 3j + 4k, b = 5j + 5k = 0i + 5j + 5k