IV. TIEN TDM DAY HOC
3. Dieu kien de hai vectd cung phiTdng
a) Muc dich: Giiip HS td tinh chdt trin rut ra dieu kiin de hai vecto cung phuong, hai vecto cung chieụ
b) Hudng thuc Men
Thuc Men [?jj trang 21 SGK vd rdt ra kii ludn ve hai vecto cdng phuong.
- Thuc Men [ ? ^ trang 21 SGK vd riit ra kii ludn ve ba diem thdng hdng.
- Cho HS ldm bdi todn 3 nhdm khdc sdu kiín thifc.
c) Qud trinh thuc hien
TT TT TT ; \ if / c V — > • •si > < j 1 1 1 i i • i i j i : 1 X I i Hinh 24
• Thuc hien [?lj trang 21 SGK va rut ra két luan ve hai vecta cung phuang.
GV thirc hien thao tac nay trong 5'.
Hoat đng cua GV
Cdu hdi 1
Hay tim cac sd k sao cho b = kd
Cdu hdi 2
Hay tim cac so m sao cho c =md
Cdu hdi 3
Hay tim cac sd n sao cho b = nc
Cdu hdi 4
Hay tim cac so p sao cho x = pU
Cdu hdi 5
Hay tim cac sd q sao cho y = qụ
Hoat đng cua HS
Gen y trd ldi edu hdi 1
1
Ggi y trd ldi edu hdi 2
5 m = - — m = - —
2
Gtyi y trd ldi cdu hdi 3
3
n = — .
5
Ggi y trd ldi cdu hdi 4
p = - 3 .
Ggi y trd ldi cdu hdi 5
q= - 1 .
Tong quat
Vecto b ciing phifOng vdi vecto a (a ^Q) khi vd chi khi ed sd k sao ehob-kd.
• Thuc hien [^2] trang 21 SGK va rut ra két luan ve ba diem thang hang.
GV cd the trd ldi ngay: Vi neua = 0, thi Vk, ka luon cung phuong vdi mgi vectạ Nhung khdng cd sd k ndo de b = ^.0 vdi b^i)
Dieu kien de ba diem thdng hang
Dieu kiin cdn vd du diba diem phdn biit A, B, C thdng hdng Id cd sd k sao cho AB = kAC.