Math Problem Statement

Given: ∠ABC = 114°, ∠DHE = 25°, ∠EHF = 41°, ∠ABC and ∠GHF are supplementary. Prove: ∠DHF ≅ ∠GHF.

Solution

To solve this problem and prove that DHFGHF\angle DHF \cong \angle GHF, let's break down the given information and organize the steps.

Given:

  1. ABC=114\angle ABC = 114^\circ
  2. DHE=25\angle DHE = 25^\circ
  3. EHF=41\angle EHF = 41^\circ
  4. ABC\angle ABC and GHF\angle GHF are supplementary, meaning their measures add up to 180180^\circ.

To Prove:

DHFGHF\angle DHF \cong \angle GHF

Plan:

We are asked to prove that two angles are congruent, specifically DHF\angle DHF and GHF\angle GHF. This involves establishing that their measures are equal.

Steps:

  1. Calculate GHF\angle GHF: Since ABC\angle ABC and GHF\angle GHF are supplementary, we can calculate the measure of GHF\angle GHF by subtracting the measure of ABC\angle ABC from 180 degrees: GHF=180114=66\angle GHF = 180^\circ - 114^\circ = 66^\circ

  2. Calculate DHF\angle DHF: DHF=DHE+EHF\angle DHF = \angle DHE + \angle EHF Substituting the given values: DHF=25+41=66\angle DHF = 25^\circ + 41^\circ = 66^\circ

  3. Conclusion: Since DHF=66\angle DHF = 66^\circ and GHF=66\angle GHF = 66^\circ, we conclude that: DHFGHF\angle DHF \cong \angle GHF

Two-Column Proof:

StatementReason
1. ABC=114\angle ABC = 114^\circ, DHE=25\angle DHE = 25^\circ, EHF=41\angle EHF = 41^\circGiven
2. ABC\angle ABC and GHF\angle GHF are supplementaryGiven
3. GHF=180ABC=66\angle GHF = 180^\circ - \angle ABC = 66^\circDefinition of supplementary angles
4. DHF=DHE+EHF=66\angle DHF = \angle DHE + \angle EHF = 66^\circAngle Addition Postulate
5. DHF=GHF\angle DHF = \angle GHFSubstitution
6. DHFGHF\angle DHF \cong \angle GHFDefinition of congruent angles

Would you like more details or have any questions?

Here are 5 related questions to expand your understanding:

  1. How can we identify supplementary angles in different geometric figures?
  2. What is the Angle Addition Postulate and how is it used in geometry proofs?
  3. What is the significance of congruent angles in triangles?
  4. How do we approach solving angle relationships when parallel lines are involved?
  5. Can the method of angle addition be applied to three-dimensional shapes?

Tip: In proofs, always clearly label each step and reason to ensure logical flow and clarity.

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Math Problem Analysis

Mathematical Concepts

Geometry
Congruent Angles
Supplementary Angles

Formulas

Supplementary angles: ∠ABC + ∠GHF = 180°
Angle Addition Postulate: ∠DHF = ∠DHE + ∠EHF

Theorems

Definition of Congruent Angles
Angle Addition Postulate
Supplementary Angle Theorem

Suitable Grade Level

Grades 9-10