Math Problem Statement

For the figure shown on the right, find the value of the variable and the measures of the angles.

Solution

To solve this problem, we need to determine the value of the variable xx and find the measures of each angle in the triangle PQR\triangle PQR.

The angles are given as:

  1. P=(2x12)\angle P = (2x - 12)^\circ
  2. Q=(2x+2)\angle Q = (2x + 2)^\circ
  3. R=x\angle R = x^\circ

Step 1: Use the Triangle Angle Sum Property

The sum of the angles in a triangle is always 180180^\circ. Therefore, we can set up the following equation:

(2x12)+(2x+2)+x=180(2x - 12) + (2x + 2) + x = 180

Step 2: Simplify and Solve for xx

  1. Combine like terms: 5x10=1805x - 10 = 180

  2. Add 10 to both sides: 5x=1905x = 190

  3. Divide by 5: x=38x = 38

Step 3: Substitute x=38x = 38 into Each Angle Expression

  1. P=2x12=2(38)12=7612=64\angle P = 2x - 12 = 2(38) - 12 = 76 - 12 = 64^\circ
  2. Q=2x+2=2(38)+2=76+2=78\angle Q = 2x + 2 = 2(38) + 2 = 76 + 2 = 78^\circ
  3. R=x=38\angle R = x = 38^\circ

Final Answer

  • x=38x = 38
  • P=64\angle P = 64^\circ
  • Q=78\angle Q = 78^\circ
  • R=38\angle R = 38^\circ

Would you like further explanation or have any questions about this solution?

Follow-Up Questions

  1. How do we know the triangle angle sum property is always 180 degrees?
  2. What would happen if the sum of the angles was not 180 degrees in a triangle?
  3. How would this method change if the triangle was not a simple one (like if it was a right or obtuse triangle)?
  4. Can you calculate the side lengths if only the angles are given in a triangle?
  5. How can we verify if the calculated angles form an actual triangle?

Tip

In any triangle, always start by checking if the sum of angles equals 180 degrees to validate your calculations.

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Math Problem Analysis

Mathematical Concepts

Algebra
Triangle Angle Sum Property

Formulas

Angle sum of a triangle: angle1 + angle2 + angle3 = 180°

Theorems

Triangle Angle Sum Theorem

Suitable Grade Level

Grades 8-10