Math Problem Statement

Suppose that △QRS is isosceles with base QR. Suppose also that m∠Q = (2x + 34)° and m∠R = (5x + 10)°. Find the degree measure of each angle in the triangle.

Solution

We are tasked with finding the degree measures of each angle in the isosceles triangle QRSQRS. Here's the step-by-step breakdown:


Step 1: Identify given information

  • Triangle QRSQRS is isosceles with base QRQR, so Q\angle Q and R\angle R are the base angles and are equal: mQ=mR.m\angle Q = m\angle R.
  • We are given: mQ=(2x+34)andmR=(5x+10).m\angle Q = (2x + 34)^\circ \quad \text{and} \quad m\angle R = (5x + 10)^\circ.

Step 2: Use equality of base angles

Since Q=R\angle Q = \angle R, set the two expressions for mQm\angle Q and mRm\angle R equal: 2x+34=5x+10.2x + 34 = 5x + 10.


Step 3: Solve for xx

  1. Subtract 2x2x from both sides: 34=3x+10.34 = 3x + 10.
  2. Subtract 1010 from both sides: 24=3x.24 = 3x.
  3. Divide by 33: x=8.x = 8.

Step 4: Find mQm\angle Q and mRm\angle R

Substitute x=8x = 8 into the expressions for mQm\angle Q and mRm\angle R:

  1. For mQ=2x+34m\angle Q = 2x + 34: mQ=2(8)+34=16+34=50.m\angle Q = 2(8) + 34 = 16 + 34 = 50^\circ.

  2. For mR=5x+10m\angle R = 5x + 10: mR=5(8)+10=40+10=50.m\angle R = 5(8) + 10 = 40 + 10 = 50^\circ.

Thus: mQ=mR=50.m\angle Q = m\angle R = 50^\circ.


Step 5: Find mSm\angle S (the vertex angle)

In a triangle, the sum of the interior angles is 180180^\circ. Therefore: mQ+mR+mS=180.m\angle Q + m\angle R + m\angle S = 180^\circ. Substitute mQ=50m\angle Q = 50^\circ and mR=50m\angle R = 50^\circ: 50+50+mS=180.50 + 50 + m\angle S = 180. Simplify: mS=180100=80.m\angle S = 180 - 100 = 80^\circ.


Final Answer:

The measures of the angles in QRS\triangle QRS are:

  • mQ=50m\angle Q = 50^\circ,
  • mR=50m\angle R = 50^\circ,
  • mS=80m\angle S = 80^\circ.

Summary Table:

AngleMeasure
mQm\angle Q5050^\circ
mRm\angle R5050^\circ
mSm\angle S8080^\circ

Do you need further clarification or additional steps? Let me know!

Related Questions:

  1. What are the properties of isosceles triangles?
  2. How do you solve systems of equations in geometry problems?
  3. What is the sum of interior angles of any polygon?
  4. Can you prove why the base angles of an isosceles triangle are always equal?
  5. How do you find the missing angles in a triangle given two angles?

Tip:

In an isosceles triangle, always check for equality of base angles to simplify your calculations.

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Math Problem Analysis

Mathematical Concepts

Isosceles Triangle
Algebraic Equations
Angle Sum Property of a Triangle

Formulas

Sum of angles in a triangle: m∠Q + m∠R + m∠S = 180°
Equality of base angles in an isosceles triangle: m∠Q = m∠R

Theorems

Base Angles Theorem
Triangle Angle Sum Theorem

Suitable Grade Level

Grades 8-10