Math Problem Statement

Solve ΔDEF: Given DE = 14.3, EF = 11.2, find DF and angles ∠DFE, ∠EDF.

Solution

This is a right triangle problem, and the goal is to solve the triangle DEF\triangle DEF, meaning we need to find the missing side ee (the hypotenuse) and the unknown angles.

Given:

  • DE=14.3DE = 14.3 (adjacent side to DFE\angle DFE)
  • EF=11.2EF = 11.2 (opposite side to DFE\angle DFE)

Step 1: Solve for the hypotenuse DFDF using the Pythagorean theorem:

DF=DE2+EF2DF = \sqrt{DE^2 + EF^2}

Substituting: DF=(14.3)2+(11.2)2DF = \sqrt{(14.3)^2 + (11.2)^2} DF=204.49+125.44=329.93DF = \sqrt{204.49 + 125.44} = \sqrt{329.93} DF18.16DF \approx 18.16

So, DF18.16DF \approx 18.16.

Step 2: Solve for the angles.

Finding DFE\angle DFE: We use the tangent function since: tan(DFE)=oppositeadjacent=EFDE\tan(\angle DFE) = \frac{\text{opposite}}{\text{adjacent}} = \frac{EF}{DE} Substitute: tan(DFE)=11.214.30.7832\tan(\angle DFE) = \frac{11.2}{14.3} \approx 0.7832 Taking the arctangent: DFE=tan1(0.7832)38.28\angle DFE = \tan^{-1}(0.7832) \approx 38.28^\circ

Finding EDF\angle EDF: The sum of angles in a triangle is 180180^\circ, and since one angle is 9090^\circ: EDF=90DFE\angle EDF = 90^\circ - \angle DFE EDF=9038.2851.72\angle EDF = 90^\circ - 38.28^\circ \approx 51.72^\circ

Final Solution:

  1. DF18.16DF \approx 18.16
  2. DFE38.28\angle DFE \approx 38.28^\circ
  3. EDF51.72\angle EDF \approx 51.72^\circ

Would you like further details or explanations?


Follow-up Questions:

  1. How do you apply the Pythagorean theorem in other cases?
  2. What trigonometric function works best when you know two sides?
  3. How would you calculate angles if given all three sides?
  4. Can you explain the relationship between the angles and sides of a triangle?
  5. How does the tangent function help in solving right triangles?

Tip:

Always verify your calculations with a different method (like sine or cosine) to ensure accuracy!

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Math Problem Analysis

Mathematical Concepts

Right Triangle Geometry
Trigonometry

Formulas

Pythagorean theorem: a² + b² = c²
Tangent function: tan(θ) = opposite/adjacent
Sum of angles in a triangle: 180°

Theorems

Pythagorean Theorem

Suitable Grade Level

Grades 8-10