(1) Did you find the advertisement? →(AB? →AC? →? ) value;
(2) judging AE? →(AB? →AC? →? Whether the value of) is constant, and explain the reasons;
(3) If AC⊥BC, ask for AF? →(FB? →? +FC? →? The maximum value of).
Scalar product operation of plane vector
(1) According to the vector parallelogram rule,
advertisement
=
1
2
(
ab blood type
+
Alternating current
), so you can bring it in to solve it.
(2)
Automatic exposure device
(
ab blood type
-
Alternating current
) is a constant, just look it up.
Automatic exposure device
=
advertisement
+
Delaware
Bring it in, because DE⊥BC, so
Delaware
(
ab blood type
-
Alternating current
)=
Delaware
Civil band
=0, so we can find its value.
(3) Because
Freight bill
+
Football club
=2
disk drive
, so
very
(
Freight bill
+
Football club
)=2
very
disk drive
At this time,
very
and
disk drive
* * * line, can be used.
advertisement
Express delivery. set up
very
=λ
advertisement
, then
disk drive
=( 1-λ)
advertisement
So bring it in and you get 2λ( 1-λ).
advertisement
2. Find the length of AD according to the conditions.
( 1)AD? →(AB? →AC? →? )= 12(AB? →? +AC? →? )(AB? →AC? →? )= 12(AB? →? 2? AC? →? 2)=4= 12(AB? →? 2? AC? →? 2)=4,
(2)AE? →(AB? →AC? →? )=(AD? →? +DE? →? )? (AB? →AC? →? )=AD? →(AB? →AC? →? )+DE? →CB? →? =4,
∴AE? →(AB? →AC? →? ) is a constant.
(3)∵AC⊥BC,|AB? →? |=3,|AC? →? |= 1;
∴|BC? →? |=22√,|DC? →? |=2√;
∴|AD? →? |= 1+2? √=3√, set AF? →? =λAD? →? What about FD? →? =( 1? λ)AD? →? ;
∴AF? →(FB? →? +FC? →? )=λAD? →(2FD? →? )=λAD? →[2( 1? λ)AD? →? ]=6λ( 1? λ)=? 6(λ? 12)2+32
∴λ= 12,AF? →(FB? →? +FC? →? ) take the maximum value of 32.