Math Problem Statement

In the figures below, ΔABC is congruent to ΔDEF. ∠ABC = 95°, DF = 12 cm, DE = 5 cm, and ∠DEF = 50°. Find the values of x, y, and z.

Solution

Let's analyze and solve the problem based on the information given in the image.

The problem provides two congruent triangles, ABC\triangle ABC and DEF\triangle DEF, with specific measurements and angles:

  1. ABC=95\angle ABC = 95^\circ
  2. DF=12cmDF = 12 \, \text{cm}, DE=5cmDE = 5 \, \text{cm}
  3. DEF=50\angle DEF = 50^\circ

We are asked to find the values of:

  • (a) xx (side ACAC in ABC\triangle ABC),
  • (b) yy (angle BAC\angle BAC in ABC\triangle ABC),
  • (c) zz (angle DFE\angle DFE in DEF\triangle DEF).

Since the triangles are congruent, corresponding sides and angles are equal. Let’s find each of the values:

(a) xx

Since ABCDEF\triangle ABC \cong \triangle DEF, side ACAC in ABC\triangle ABC is congruent to side DEDE in DEF\triangle DEF. Therefore: x=DE=5cmx = DE = 5 \, \text{cm}

(b) yy

In ABC\triangle ABC, we have: ABC=95andABCDEF\angle ABC = 95^\circ \quad \text{and} \quad \triangle ABC \cong \triangle DEF Since the sum of angles in a triangle is 180180^\circ, we can calculate yy (i.e., BAC\angle BAC) by: y=1809550=35y = 180^\circ - 95^\circ - 50^\circ = 35^\circ

(c) zz

Since ABCDEF\triangle ABC \cong \triangle DEF, angle zz in DEF\triangle DEF corresponds to angle yy in ABC\triangle ABC. Therefore: z=y=35z = y = 35^\circ

Final Answers:

  1. x=5cmx = 5 \, \text{cm}
  2. y=35y = 35^\circ
  3. z=35z = 35^\circ

Would you like further details on these solutions, or do you have additional questions?


Here are some related questions for further practice:

  1. How do we prove triangles are congruent using the Side-Angle-Side (SAS) criterion?
  2. If the triangles were not congruent, how would that affect our answers?
  3. Can you calculate the area of DEF\triangle DEF using the given information?
  4. What are other methods to determine unknown angles in a triangle?
  5. How would you solve for xx, yy, and zz if only one angle and two sides were known?

Tip: Remember, the sum of interior angles in any triangle is always 180180^\circ.

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Math Problem Analysis

Mathematical Concepts

Congruence of Triangles
Angle Sum Property
Triangle Properties

Formulas

Sum of interior angles in a triangle = 180°

Theorems

Congruent triangles have equal corresponding sides and angles

Suitable Grade Level

Grades 8-10