(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.