Give the triangle ABC have inscribed circles (I). (I) contact BC, CA, AB at D, E, F. Let M and N be the midpoints of BC and IA. DF \(\cap\) IE = {P}, DE \(\cap\) IF = {Q}. Prove that: MN \(\bot\) PQ

Let I be the incentre of acute triangle ABC with \(AB\ne AC\). The incircle \(\omega\)of ABC is tangent to sides BC, CA and AB at D, E, F respectively. The line through D pependicular to EF meets \(\omega\)again at R. Line AR meets \(\omega\)again at P. The circumcircles of triangles PCE and PBF meet again at Q. Prove that lines DI and PQ meet on the line through A perpendicular to...

0

LS

Lê Song Phương

CTVHS

8 tháng 1 2022

1

PT

Phạm Thị Ngọc Yến

8 tháng 1 2022

Ủa sao toàn tiếng Anh vậy

1. Two bisector BD and CE of the triangle ABC intersect at O. Suppose that BD.CE = 2BO.OC . Denote by H the point in BC such that .\(OH⊥BC\) . Prove that AB.AC = 2HB.HC 2. Given a trapezoid ABCD with the based edges BC=3cm , DA=6cm ( AD//BC ). Then the length of the line EF ( \(E\in AB,F\in CD\) and EF // AD ) through the intersection point M of AC and BD is ............... ? 3. Let ABC be an equilateral triangle and a point M inside the triangle such that \(MA^2=MB^2+MC^2\) . Draw an...

PT

Phạm Thị Hằng

21 tháng 12 2016

#Toán lớp 8

0

LT

Lê Tài Bảo Châu

23 tháng 4 2019

Given acute triangle ABC(AB<AC). O is the midpoint of BC, BM and CN are the altitudes of triangle ABC. The bisectors of angle \(\widehat{BAC}\)and \(\widehat{MON}\)meet each other at D. AD intesects BC at E. Prove that quadrilateral BNDE is inscribed in a circle.s

( HELP ME )

#Toán lớp 8

0

CA

CHU ANH TUẤN

30 tháng 8 2018

Given the Triangle ABC and the point M inside the triangle (M don't belong on any sides of triangle).let I be the intersection point of the line BM and the side AC

a, compare MA to MI+MB,then prove that MA +MB<IB+IA

b, compare IB to IC+CB, then prove that IB+IA<CA+CB

c, Demonstrate the inequality MA+MB<CA+CB

#Toán lớp 7

0

CA

CHU ANH TUẤN

29 tháng 8 2018

Given the Triangle ABC and the point M inside the triangle (M don't belong on any sides of triangle).let I be the intersection point of the line BM and the side AC

a, compare MA to MI+MB,then prove that MA +MB<IB+IA

b, compare IB to IC+CB, then prove that IB+IA<CA+CB

c, Demonstrate the inequality MA+MB<CA+CB

#Toán lớp 7

1

S

sieuvegeto

29 tháng 8 2018

Môn j mà hay zâỵ sao dịch dc lên gogle dịch à

Given a triangle ABC. D is a point on AB and E is a point on AC so that DE//BC and \(\frac{BC}{DE}=\sqrt{2}\), F is a point on BC and G is a point on AB so that FG//AC and \(\frac{AC}{FG}=\sqrt{2}\), H is a point on BC and I is a point on AC so that HI//AB and \(\frac{AB}{HI}=\sqrt{2}\). FG meets HI at X, DE meets HI at Y and DE meets FG at Z.i) Prove that \(DY=ZE\)ii) Find the exactly value of the...

LS

Lê Song Phương

CTVHS

6 tháng 2 2022

1

XO

Xyz OLM

7 tháng 2 2022

I) Hình bạn tự vẽ nha

Ta có DY//BH ; YH//DB

=> DYHB hình bình hành => DY = HB

Tương tự được ZE = FC

mà \(\frac{BH}{BC}=1-\frac{HC}{BC}=1-\frac{1}{\sqrt{2}}\)\(\left(\Delta HIC\approx\Delta BAC;\frac{AB}{IH}=\sqrt{2}\right)\)(1)

Tương tự được \(\frac{FC}{BC}=1-\frac{BF}{BC}=1-\frac{1}{\sqrt{2}}\)(2)

Từ (1) ; (2) => BH = FC hay DY = ZE

NN

Nguyệt Nguyệt

21 tháng 3 2017

Let ABC be an isoceles triangle (AB = AC) and its area is 501cm². BD is the internal bisector of the angle ABC (D ∈ AC), E is a point on the opposite ray of CA such that CE = CB. I is a point on BC such that CI = 1/2 BI. The line EI meets AB at K, BD meets KC at H. Find the area of the triangle AHC.

#Toán lớp 8

1

B

BW_P&A

21 tháng 3 2017

bái phục giờ vẫn còn thi toán tiếng anh á ghê á nha

thi xog cấp tỉnh là vứt luôn nhác thi lắm luôn

BD

Bình Dị

22 tháng 3 2017

vẫn còn qg mà mà bạn

CD

Cù Đức Anh

23 tháng 3 2022

Circle O has diameters AB and CD perpendicular to each other. AM is any chord intersecting CB at N.I is the center of the circle inscribed in triangle AMB. Prove that M, I, D are collinear points

2

ZT

Zero Two

23 tháng 3 2022

ô hello ZT

CD

Cù Đức Anh

23 tháng 3 2022

ét o ét, cần giúp