Help proving a trianlge is isosceles

  • Thread starter Thread starter chim richalds
  • Start date Start date
Click For Summary
SUMMARY

The discussion focuses on proving that triangle A'EF is isosceles, where A' is the midpoint of side BC in triangle ABC. The key steps involve demonstrating that the lengths A'E and A'F are equal or that angles A'EF and A'FE are congruent. A crucial hint provided is to draw a circle with diameter BC, which helps establish right angles inscribed in a semicircle. The proof requires showing that segments A'F and A'E are congruent to segment A'C.

PREREQUISITES
  • Understanding of triangle properties, specifically isosceles triangles
  • Knowledge of altitude and midpoint concepts in geometry
  • Familiarity with inscribed angles and circles in geometry
  • Basic skills in geometric proof techniques
NEXT STEPS
  • Study the properties of isosceles triangles and their proofs
  • Learn about inscribed angles and their relationships in circles
  • Explore geometric constructions involving midpoints and altitudes
  • Practice solving problems related to triangle congruence criteria
USEFUL FOR

Students studying geometry, particularly those tackling problems involving triangle properties and proofs. This discussion is beneficial for anyone seeking to enhance their understanding of geometric relationships and proof strategies.

chim richalds
Messages
1
Reaction score
0
Hi. I'm seriously stuck on this problem. I don't even know where to begin.

Homework Statement


Suppose triangle ABC is an acute angle triangle. Let the bases of the altitudes to B and C be E and F, respectively, and let A' be the midpoint of BC. Prove that triangle A'EF is isosceles.

Homework Equations


The Attempt at a Solution


I know that I have to show that A'E and A'F are the same length or that angles A'EF and A'FE are congruent in order to prove the triangle is isosceles. I'm clueless though.There's a typo in the topic title. Sorry.
 
Physics news on Phys.org
Hint: Draw the circle with diameter BC and observe the right angles are inscribed in a semicircle.
 
First, show that A'F congruent to A'C. (Try drawing A'G such that G lies on CF and A'G is perpendicular to CF)

Use the same process to show that A'E congruent to A'C
 

Similar threads

Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 18 ·
Replies
18
Views
5K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K