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Section 12.3: Triangles — Practice Questions

  1. 1. An isosceles triangle has a base angle measuring $32^\circ$. What is the measure in degrees of the vertex angle? ___

  2. 2. An isosceles right triangle has one $90^\circ$ angle and two equal acute angles. What is the measure of each acute angle in degrees? ___

  3. 3. Two interior angles of a triangle are $50^\circ$ and $110^\circ$. What is the measure in degrees of the third interior angle? ___

  4. 4. Is it possible for the vertex angle in an isosceles triangle to be obtuse?

    • A. Yes
    • B. No
  5. 5. An equilateral triangle has three equal angles. What is the measure of each angle in degrees? ___

  6. 6. A triangle has two angles measuring $131^\circ$ and $17^\circ$. Find the measure of the third angle in degrees. ___

  7. 7. A regular octagon is composed of eight identical isosceles triangles with their vertices at the center. What is the measure of each interior angle of the octagon in degrees? ___

  8. 8. Which statement explains why a triangle cannot have interior angles measuring $27^\circ$, $58^\circ$, and $103^\circ$?

    • A. The sum of the angles is not $180^\circ$.
    • B. A triangle cannot have an obtuse angle.
    • C. All angles must be equal.
    • D. Two angles cannot be acute.
  9. 9. In a right triangle, the largest angle is three times the smallest angle. What are the measures of the three angles?

    • A. $30^\circ, 60^\circ, 90^\circ$
    • B. $25^\circ, 65^\circ, 90^\circ$
    • C. $45^\circ, 45^\circ, 90^\circ$
    • D. $20^\circ, 70^\circ, 90^\circ$
  10. 10. Two angles of a triangle measure $23^\circ$ and $48^\circ$. What is the measure in degrees of the third angle? ___