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What have we got to prove?

Whether we have to prove a triangle as an Isoseles triangle or prove a property of an isoseles triangle. Hey, do u go to ALHS, i had that same problem on my test today. Greenehornet15@Yahoo.com

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Q: How to prove an isosceles triangle with one angle bisector?
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How can you prove that a triangle is an isosceles triangle with some examples?

An isosceles triangle has 3 sides 2 of which are equal in length An isosceles triangle has 3 interior angles 2 of which are the same size


How do you prove the diagonals of an isosceles triangle congruent?

You can't because triangles do not have diagonals but an isosceles triangle has 2 equal sides


What do you need to do to prove a line is an angle bisector of an angle?

Draw a perpendicular to that line and extend the arms of the angle to meed the perpendicular drawn earlier. Check if the line is bisecting the perpendicular, if yes, then the line is a bisector of the angle. :)


How do you prove the isosceles triangle theorem?

The isosceles triangle theorem states: If two sides of a triangle are congruent, then the angles opposite to them are congruent Here is the proof: Draw triangle ABC with side AB congruent to side BC so the triangle is isosceles. Want to prove angle BAC is congruent to angle BCA Now draw an angle bisector of angle ABC that inersects side AC at a point P. ABP is congruent to CPB because ray BP is a bisector of angle ABC Now we know side BP is congruent to side BP. So we have side AB congruent to BC and side BP congruent to BP and the angles between them are ABP and CBP and those are congruent as well so we use SAS (side angle side) Now angle BAC and BCA are corresponding angles of congruent triangles to they are congruent and we are done! QED. Another proof: The area of a triangle is equal to 1/2*a*b*sin(C), where a and b are lengths of adjacent sides, and C is the angle between the two sides. Suppose we have a triangle ABC, where the lengths of the sides AB and AC are equal. Then the area of ABC = 1/2*AB*BC*sin(B) = 1/2*AC*CB*sin(C). Canceling, we have sin(B) = sin(C). Since the angles of a triangle sum to 180 degrees, B and C are both acute. Therefore, angle B is congruent to angle C. Altering the proof slightly gives us the converse to the above theorem, namely that if a triangle has two congruent angles, then the sides opposite to them are congruent as well.


How do you prove a right angle triangle?

You cannot prove "a right angle triangle". You may or may not be able to prove statements about right angled triangles but that will depend on the particular statement.

Related questions

Angle bisector of angleA of triangleABC is perpendicular to BC prove it is isosceles?

Let D represent the point on BC where the bisector of A intersects BC. Because AD bisects angle A, angle BAD is congruent to CAD. Because AD is perpendicular to BC, angle ADB is congruent to ADC (both are right angles). The line segment is congruent to itself. By angle-side-angle (ASA), we know that triangle ADB is congruent to triangle ADC. Therefore line segment AB is congruent to AC, so triangle ABC is isosceles.


What is the angle bisector concurrency theorem?

the definition of an angle bisector is a line that divides an angle into two equal halves. So you need only invoke the definition to prove something is an angle bisector if you already know that the two angles are congruent.


How do i prove if the base angles of a triangle are congruent then the triangle is isosceles?

Suppose you have triangle ABC with base BC, and angle B = angle C. Draw the altitude AD.Considers triangles ABD and ACDangle ABD = angle ACD (given)angle ADB = 90 deg = angle ACDtherefore angle BAD = angle CADAlso the side AD is common to the two triangles.Therefore triangle ABD is congruent to triangle ACD (ASA) and so AB = AC.That is, triangle ABC is isosceles.


How can you prove that a triangle is an isosceles triangle with some examples?

An isosceles triangle has 3 sides 2 of which are equal in length An isosceles triangle has 3 interior angles 2 of which are the same size


How do you prove an isosceles triangle?

an isisceles triangle is a triangle with atleast two sides congruent.


Is an isosceles obtuse triangle possible?

Yes it is possible. Obtuse means the triangle contains an angle which is greater than 90 degrees, and isosceles means the triangle has two sides of the same length. So to prove this in the easiest way possible, you can make a dot on your page, measure 91 or more degrees and draw two equal length lines out at this angle, then connect these two lines to make an obtuse isosceles triangle.


How do you prove the diagonals of an isosceles triangle congruent?

You can't because triangles do not have diagonals but an isosceles triangle has 2 equal sides


How do you prove that isosceles triangles have three equal sides?

If You Prove An Isosceles Triangle To Have Three Equal Sides. You Now Have Disproved It As Being An Isosceles Triangle. So Even If You Could You Would Now Have An Equilateral Triangle. I Just Can`t See A Way This Can Be Done.


What do you need to do to prove a line is an angle bisector of an angle?

Draw a perpendicular to that line and extend the arms of the angle to meed the perpendicular drawn earlier. Check if the line is bisecting the perpendicular, if yes, then the line is a bisector of the angle. :)


How can you prove a triangle ABC is isosceles if angle BAD is congruent to angle CAD and line AD is perpendicular to line Bc?

Given: AD perpendicular to BC; angle BAD congruent to CAD Prove: ABC is isosceles Plan: Principle a.s.a Proof: 1. angle BAD congruent to angle CAD (given) 2. Since AD is perpendicular to BC, then the angle BDA is congruent to the angle CDA (all right angles are congruent). 3. AD is congruent to AD (reflexive property) 4. triangle BAD congruent to triangle CAD (principle a.s.a) 5. AB is congruent to AC (corresponding parts of congruent triangles are congruent) 6. triangle ABC is isosceles (it has two congruent sides)


Is an equilateral triangle always or sometimes called an isosceles?

If you can only prove two sides of an apparently equilateral triangle to be congruent then you have to use isosceles.


If two angle bisectors of a triangle are congruent then prove that triangle is isosceles?

If two angle bisectors of a triangle are congruent, then the triangle is isosceles. This is because the angle bisectors of a triangle are concurrent and the angle bisectors of a triangle that are congruent divide the opposite sides of the triangle into two equal segments. So if two angle bisectors are congruent, the sides opposite those angles are also equal, making the triangle isosceles.