Question

problem 8: spiral review determine the missing angle measure in the isosceles triangle. show or explain your thinking.

Explanation:

Step1: Recall angle - sum property of a triangle

The sum of the interior angles of a triangle is 180°. Let the two equal angles in the isosceles triangle be \(x\). We know one angle is 120°. So, \(x + x+120^{\circ}=180^{\circ}\).

Step2: Simplify the equation

Combining like - terms, we get \(2x+120^{\circ}=180^{\circ}\). Subtract 120° from both sides: \(2x=180^{\circ}- 120^{\circ}\), so \(2x = 60^{\circ}\).

Step3: Solve for \(x\)

Divide both sides of the equation \(2x = 60^{\circ}\) by 2. We have \(x=\frac{60^{\circ}}{2}=30^{\circ}\).

Answer:

30°