Ve tam giac abc biet goc b=60° ; BA=3cm ;BC=5cm . Tren tam giac abc ve tia Bx sao cho CBx =30° .
Tinh ABx , tia bx la tia gi cua goc ABC? Vi sao
GIUP MINH !!!! SANG MAI MINH NOP
cho tam giac abc co goc a=90 do,giai tam giac abc biet ab=6cm,goc b=60 do
Ta có: ΔABC vuông tại A
nên \(\widehat{B}+\widehat{C}=90^0\)
hay \(\widehat{C}=30^0\)
Xét ΔABC vuông tại A có
\(BC=AB:\sin30^0=6:\dfrac{1}{2}=12\left(cm\right)\)
\(\Leftrightarrow AC=6\sqrt{3}\left(cm\right)\)
cho tam giac ABC ve tia phan giac AD tai A biet ADB=80 B=3/2C tinh cac goc cua tam giac ABC
\(\widehat{ADC}=180^0-80^0=100^0\)
Ta có: \(\widehat{ADB}+\widehat{B}+\widehat{BAD}=\widehat{ADC}+\widehat{C}+\widehat{CAD}\)
mà \(\widehat{BAD}=\widehat{CAD}\)
nên \(\widehat{ADB}+\widehat{B}=\widehat{ADC}+\widehat{C}\)
=>\(\widehat{B}-\widehat{C}=100^0-80^0=20^0\)
=>\(\dfrac{3}{2}\widehat{C}-\widehat{C}=20^0\)
=>\(\widehat{C}=40^0\)
\(\widehat{B}=\dfrac{3}{2}\cdot40^0=60^0\)
\(\widehat{BAC}=180^0-40^0-60^0=80^0\)
Cho tam giac ABC vuong can tai A. Ve phia ngoai tam giac ABC, ve tam giac BCD vuong can tai B. Ke BH vuong goc vs CD. Biet CD = căn bậc 128 cm. Do dai AH la
CHO TAM GIAC ABC CO GOC ABC=2ACB
A)CM:GOC ACB <60 DO
b)TIM DIEU KIEN vE GOC ACB DE TAM GIAC ABC NHON
1 cho tam giac abc can a , goc a bang 40 do lay d khac phia b so voi ac thoa man goc cad bang 60 do goc cad bang 80 do chung minh bd vuong goc voi ac
2 cho tam giac abc vuong can a . d la diem bat ki tren ab. tren nua mat phang bo ab tu c ve tia bx sao cho goc abx bang 135 do. duong thang vuong goc voi dc ve tu d cat bx o e . chung minh tam giac dec vuong can
3 cho tam giac abc can b goc abc bang 80 do , i la diem trong tam giac sao cho goc iac bang 10 do, ica bang 30 do tinh goc abi
4 cho tam giac abc can a co goc a bang 100 do , bc =a, ac =b ve phia ngoai tam giac abc ve tam giac abd can d co goc adb bang 140 do tinh ch vi tam giac adb theo a,b
ve hinh gium minh voi , xin mn day
cho tam giac ABC co goc A =60 do, goc B= 70 do. Ve tia phan giac cua goc A cat canh BC tai D.Tinh goc ADC, ADB
tam giac ABC co goc A=90 do ve ra ngoai tam giac ABC cac tam giac deu ABD va ACE, BE cat CD tai I. CMR:
a)BE=CD
b)tam giac BDE can
c)goc EIC=60 do va IA la P/G cua goc DIE
Cho tam giac ABC vuong tai A :
A.Cho biet AB=9cm;BC=15cm.Tinh AC roi so sanh cac goc cua tam giac ABC
B.Tren BC lay D sao cho BD=BA.Tu D ve duong thang vuong goc voi BC cat AC tai E.Chung minh tam giac EBA= tam gaic EBD
C.Tren tia doi cua tia ED lay diem F sao cho DF=DE.Chung minh rang goc DEC= goc DCE
D.Tu D ve DM vuong goc CE ; DN vuong goc CF (M thuoc CE ; N thuoc CF )
Cho goc ECF=60 do va CD= 10cm.Tinh MN (lam tron ket qua den hang don vi )
Cho tam gia ABC vuong tai B. Ve duong cao BH. tim so do cac goc cua tam giac ABC biet HC-HB=AB
nao giai duoc nhanh va dung nhat cho 10 cai k thiet!
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