Math Problem Statement

Suppose that △ABC is isosceles with base CA. Suppose also that m∠B = (2x + 36)° and m∠C = (5x - 6)°. Find the degree measure of each angle in the triangle.

Solution

To solve for the angles in the isosceles triangle ABC\triangle ABC, where base CACA is given, and the angles mBm\angle B and mCm\angle C are expressed as 2x+362x + 36 and 5x65x - 6, respectively, follow these steps:


Step 1: Recall the triangle angle sum property.

The sum of all angles in a triangle equals 180180^\circ: mA+mB+mC=180.m\angle A + m\angle B + m\angle C = 180^\circ.


Step 2: Use the isosceles property.

Since ABC\triangle ABC is isosceles with base CACA, the two base angles mBm\angle B and mCm\angle C are congruent: mB=mC.m\angle B = m\angle C. From the problem: mB=2x+36andmC=5x6.m\angle B = 2x + 36 \quad \text{and} \quad m\angle C = 5x - 6. Thus: 2x+36=5x6.2x + 36 = 5x - 6.


Step 3: Solve for xx.

Simplify the equation: 2x+36=5x6.2x + 36 = 5x - 6. Subtract 2x2x from both sides: 36=3x6.36 = 3x - 6. Add 6 to both sides: 42=3x.42 = 3x. Divide by 3: x=14.x = 14.


Step 4: Find mBm\angle B and mCm\angle C.

Substitute x=14x = 14 into the expressions for mBm\angle B and mCm\angle C: mB=2x+36=2(14)+36=28+36=64,m\angle B = 2x + 36 = 2(14) + 36 = 28 + 36 = 64^\circ, mC=5x6=5(14)6=706=64.m\angle C = 5x - 6 = 5(14) - 6 = 70 - 6 = 64^\circ.


Step 5: Find mAm\angle A.

Using the angle sum property: mA+mB+mC=180.m\angle A + m\angle B + m\angle C = 180^\circ. Substitute mB=64m\angle B = 64^\circ and mC=64m\angle C = 64^\circ: mA+64+64=180.m\angle A + 64 + 64 = 180. Simplify: mA=180128=52.m\angle A = 180 - 128 = 52^\circ.


Final Answer:

The degree measures of the angles are: mA=52,mB=64,mC=64.m\angle A = 52^\circ, \quad m\angle B = 64^\circ, \quad m\angle C = 64^\circ.


Do you want further clarification or additional steps? Here are 5 related questions:

  1. How would the solution change if the triangle were equilateral?
  2. What if mBm\angle B and mCm\angle C were not congruent? How would we solve for xx?
  3. Can you generalize the angle sum property for a quadrilateral?
  4. What happens to the angle measures if we increase xx further?
  5. How do you verify that the triangle satisfies the isosceles property?

Tip: Always verify that the calculated angles add up to 180180^\circ when solving for angles in any triangle.

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Math Problem Analysis

Mathematical Concepts

Triangle Angle Sum Property
Isosceles Triangle Properties
Solving Linear Equations

Formulas

m∠A + m∠B + m∠C = 180°
Base angles of an isosceles triangle are equal

Theorems

Triangle Angle Sum Theorem
Isosceles Triangle Theorem

Suitable Grade Level

Grades 8-10