u=(a,1,0)
v=(2, -1,2)
IuI= √ (a²+1)
IvI=√ (4+1+4)= 3
u.v=(a,1,0)(2, -1,2)= 2a-1
cos 45=√2/2
uv=IuIIvI vos46
2a-1=√(a²+1) .3 .√2/2,,, ao quadrado
4a²-4a+1=(a²+1) .9 . 2/4
8a²-8a +2=9a²+9
a²+8a+7=0
Δ= 64-28=36
a=(-8+-6)/2
a=-7
a=- 1
Resp
-7
ou
-1
#
Vide angulo entre dois vetores
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Verified answer
u=(a,1,0)
v=(2, -1,2)
IuI= √ (a²+1)
IvI=√ (4+1+4)= 3
u.v=(a,1,0)(2, -1,2)= 2a-1
cos 45=√2/2
uv=IuIIvI vos46
2a-1=√(a²+1) .3 .√2/2,,, ao quadrado
4a²-4a+1=(a²+1) .9 . 2/4
8a²-8a +2=9a²+9
a²+8a+7=0
Δ= 64-28=36
a=(-8+-6)/2
a=-7
a=- 1
Resp
-7
ou
-1
#
Vide angulo entre dois vetores