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1. Prove that any straight line drawn to form the vertex of a triangle to the base is bisected by the straight line that joins the midpoints of the other sides.

2. AD and BE are the altitudes of an isoscles triangle ABC with AB = BC. Prove that AE = BD

3. In a triangle ABC, the bisector of angle A meets base BC at D. Prove that AB>BD

4. In a triangle PQR, S is any point on QR. Prove that PQ + QR + PR > 2PS

5. If two isosceles triangles have a common base, then prove that the line joining their vertices bisects them at right angles.

6. In triangle ABC, D is the midpoint of AB and P is any point on BC. A line CQ is drawn parallel to PD to meet AB at Q.
Prove that ar(BPQ) = 1/2 ar(ABC)

2006-11-21 20:57:52 · 6 answers · asked by Akilesh - Internet Undertaker 7 in Science & Mathematics Mathematics

Can anyone answer something other than the first one?

2006-11-22 02:52:37 · update #1

6 answers

Your first Question:

Now,

Imagine a Triangle with vertices ABC.
Any line from A to BC is AD. D is the point of intersection on BC.

Let E and F be the midpoints of Sides AB anc AC respectively.

Join E and F to meet AD in G.

Now for the proof:
Take Triangles AGE and ADB these two are similar.

Reason being that EF would be parallel to BC from Mid Point theorem. Therefore, the two triangles will be similar as Angle E and Angle B are equal and Angle A is common.

Now take Triangle ADB, E is the mid point of AB and EG is parallel to BD there for from Converse of Midpoint Theorem G becomes the Midpoint of AD.

Hence proved.

2006-11-21 21:09:53 · answer #1 · answered by Shashank B 2 · 1 0

1.let ABC be the triangle and let AD be any line from vertex A onto D,a point on BC
letEF be the line joiningthe midpoints of AB and AC respectively.
To Prove that AD is bisected by EF
let the point of intersection of AD and EF be G
To Prove that AG=GD
line EF parallel to line BC (midpoint theorem)
draw XY parallel to EF and hence BC through A
now the parallel lines XY,EF and BC make equal intercepts AE and ED on transversal AB
so by intercepts theorem they must make equal intercepts on AD also
soAG=GD
hence proved

i have done one for you
transversal

2006-11-21 21:20:22 · answer #2 · answered by raj 7 · 1 0

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2016-11-29 08:58:52 · answer #3 · answered by ? 4 · 0 0

1. By equal intercept theorem,If any 3 lines are drawn parallel to each other, the intercepts made by any 2 or more intercepts are equal and in the same line , they are proportional.
Using this theorem, we can prove the first prob.

2006-11-21 23:02:23 · answer #4 · answered by Anonymous · 1 0

______________/when it riches the line.

AD+BE=16 B because this answer as known be Hex..

A angel can't connect together 2-4 points of angels. AB>BD=C

PQ+PR+QR: SPRQ connect together.

i know this:it becomes like a dormer

And P can't be connect if near each other

2006-11-21 21:07:13 · answer #5 · answered by Anonymous · 0 1

These are the theorems and corollary of them. U can find the proof in some good trigonometry book with detailed explanation.

2006-11-21 23:42:22 · answer #6 · answered by Napster 2 · 0 1

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