answersLogoWhite

0


Best Answer

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.

User Avatar

Wiki User

15y ago
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: How do you prove the isosceles triangle theorem?
Write your answer...
Submit
Still have questions?
magnify glass
imp
Related questions

suppose you want to prove the isosceles triangle theorem by proving that JKL?

L


What is the Converse of isosceles triangle theorem?

The isosceles triangle theorem states that if two sides of a triangle are congruent, the angles opposite of them are congruent. The converse of this theorem states that if two angles of a triangle are congruent, the sides that are opposite of them are congruent.


Does the Pythagorean theorem work on isosceles triangles?

it depens if the isosceles triangle is a right triangle or not


The isosceles triangle theorem states that if two sides of a triangle are congruent then the opposite those sides are?

The isosceles triangle theorem states that if two sides of a triangle are congruent, then the angles opposite those sides are congruent.


Is Pythagorean theorem applicable on isosceles right triangle?

YES


which completes the paragraph proof?

converse of the isosceles triangle theorem


complete the paragraph proof?

converse of the isosceles triangle theorem


Does pythagorean theorem prove a triangle to be a right triangle?

Yes


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


What is the Isosceles Triangle Theorem in Geometry?

The Isosceles Triangle Theorem:If two sides of a triangle are congruent, then the angles opposite the sides are congruent.The Converse of Isosceles Triangle Theorem:If two angles of a triangle are congruent, then the sides opposite those angles are congruent.


How do you prove an isosceles triangle?

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


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