Triangle Inequality Theorems

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson
Download our mobile app to listen on the go
Get App

Questions and Answers

In $\triangle ABC$, if $AB > AC$, which of the following statements must be true according to the Side-Angle Inequality Theorem?

  • $m\angle A > m\angle C$
  • $m\angle B > m\angle C$
  • $m\angle A > m\angle B$
  • $m\angle C > m\angle B$ (correct)

Given $\triangle XYZ$ where $XY = 5$, $YZ = 8$, and $ZX = 10$. Which angle has the largest measure?

  • $\angle Y$
  • $\angle Z$
  • $\angle X$ (correct)
  • Cannot be determined

If in $\triangle PQR$, $m\angle P > m\angle Q$, which of the following statements is true according to the Angle-Side Inequality Theorem?

  • $PQ > PR$
  • $PQ > QR$
  • $PR > QR$
  • $QR > PR$ (correct)

In $\triangle DEF$, $DE = 7$, $EF = 5$, and $DF = 9$. Which angle has the smallest measure?

<p>$\angle D$ (B)</p> Signup and view all the answers

Which set of side lengths can form a triangle, according to the Triangle Inequality Theorem?

<p>4, 5, 6 (D)</p> Signup and view all the answers

Given a triangle with sides of length 7 and 9, what is a possible length for the third side according to the Triangle Inequality Theorem?

<p>15 (A)</p> Signup and view all the answers

According to the Exterior Angle Inequality Theorem, which statement is always true regarding an exterior angle of a triangle?

<p>It is greater than either of the remote interior angles. (B)</p> Signup and view all the answers

In $\triangle ABC$, if $\angle ACD$ is an exterior angle at vertex $C$, then:

<p>$m\angle ACD &gt; m\angle B$ (D)</p> Signup and view all the answers

Given two triangles, $\triangle ABC$ and $\triangle DEF$, where $AB = DE$ and $BC = EF$. If $m\angle B > m\angle E$, what can be concluded according to the Hinge Theorem?

<p>$AC &gt; DF$ (B)</p> Signup and view all the answers

Two triangles, $\triangle LMN$ and $\triangle PQR$, have $LM = PQ$ and $MN = QR$. If $LN < PR$, which statement is true according to the Converse of the Hinge Theorem?

<p>$m\angle M &lt; m\angle Q$ (D)</p> Signup and view all the answers

In $\triangle ABC$, $AB = 6$ and $BC = 8$. Which of the following is NOT a possible length for $AC$?

<p>14 (D)</p> Signup and view all the answers

If $m\angle A = 50^\circ$ and $m\angle B = 60^\circ$ in $\triangle ABC$, which side is the longest?

<p>$AB$ (A)</p> Signup and view all the answers

Given $\triangle PQR$ where $PQ = 4$, $QR = 7$, and $RP = 5$. Arrange the angles from smallest to largest.

<p>$\angle Q, \angle R, \angle P$ (A)</p> Signup and view all the answers

In $\triangle ABC$, if $AB \cong DE$, $BC \cong EF$ and $AC > DF$, what can be said about $\angle B$ and $\angle E$?

<p>$m\angle B &gt; m\angle E$ (A)</p> Signup and view all the answers

According to the Triangle Inequality Theorem, what inequality must be true for any $\triangle ABC$?

<p>$AB + BC &gt; AC$ (D)</p> Signup and view all the answers

In $\triangle XYZ$, $\angle X$ is $40^\circ$ and $\angle Y$ is $60^\circ$. Which side of the triangle is the longest?

<p>$XZ$ (A)</p> Signup and view all the answers

In triangles $\triangle ABC$ and $\triangle DEF$, $AB = DE$, $BC = EF$, and $\angle ABC > \angle DEF$. Which statement is always true?

<p>$AC &gt; DF$ (C)</p> Signup and view all the answers

In $\triangle ABC$, if side $a = 5$, side $b = 7$, which of the following is a possible value for side $c$?

<p>3 (D)</p> Signup and view all the answers

In triangles $\triangle ABC$ and $\triangle DEF$, $AB = DE$, $BC = EF$. If $AC < DF$, which is true?

<p>$m\angle B &lt; m\angle E$ (C)</p> Signup and view all the answers

In $\triangle ABC$, $m\angle A = 70^\circ$ and $m\angle B = 50^\circ$. Arrange the sides from shortest to longest.

<p>$BC &lt; AC &lt; AB$ (C)</p> Signup and view all the answers

Flashcards

Triangle Inequality Theorem 1 (Ss→Aa)

If one side of a triangle is longer than a second side, then the angle opposite the first side is larger than the angle opposite the second side.

Triangle Inequality Theorem 2 (Aa→Ss)

If one angle of a triangle is larger than a second angle, then the side opposite the larger angle is longer than the side opposite the smaller angle.

Triangle Inequality Theorem 3

The sum of the lengths of any two sides of a triangle is greater than the length of the third side.

Exterior Angle Inequality Theorem

The measure of an exterior angle of a triangle is greater than the measure of either remote interior angle

Signup and view all the flashcards

Hinge Theorem

If two sides of one triangle are congruent to two sides of another triangle, but the included angle of the first triangle is greater than the included angle of the second, then the third side of the first triangle is longer than the third side of the second.

Signup and view all the flashcards

Converse of Hinge Theorem

If two triangles have two congruent sides, then the triangle with the longer third side will have a larger angle opposite that third side

Signup and view all the flashcards

Study Notes

Triangle Inequality Theorem 1 (Ss→Aa) / Side-Angle Inequality Theorem

  • If one side of a triangle is longer than a second side, the angle opposite the first side is larger than the angle opposite the second side.
  • AM ≅ AI by construction.
  • ΔAIM is isosceles based on the definition of an isosceles triangle.
  • ∠1 ≅ ∠2 because base angles of an isosceles triangle are congruent.
  • ∠1 + ∠3 = ∠AMN according to the Angle Addition Postulate.
  • ∠AMN > ∠1 due to the property of equality.
  • ∠AMN > ∠2 is derived using the Substitution Property.
  • m∠MIN+ m∠N + m∠3 = 180 because the sum of the measures of interior angles of a triangle totals 180.
  • m∠2 + m∠MIN = 180° owing to the Linear Pair Theorem.
  • m∠MIN + m∠n + m∠3 = m∠2 + m∠MIN through the Transitive Property.
  • m∠2 = m∠N+ m∠3 via the Subtraction Property.
  • m∠2 > m∠ANM following the property of equality.
  • m∠AMN > m∠ANM (from statement 6), due to the Property of Inequality.

Triangle Inequality Theorem 2 (Aa→Ss) / Angle-Side Inequality Theorem

  • If one angle of a triangle is larger than a second angle, then the side opposite the larger angle is longer than the side opposite the smaller angle.

Triangle Inequality theorem 3

  • The sum of the lengths of any two sides of a triangle is greater than the length of the third side
  • PL ≅ LE by construction.
  • ΔLEP is isosceles according to the definition.
  • ∠1 ≅ ∠2 as base angles of an isosceles triangle are congruent.
  • ∠LPE ≅ ∠MPE through the Reflexive Property.
  • ∠1 ≅ ∠MPE by the Transitive Property.
  • m∠MEP = m∠LEM + m∠LEP via the Angle Addition Postulate.
  • m∠MEP = m∠LEM + m∠MPE due to the Transitive Property.
  • m∠MEP > m∠MPE through the Property of Inequality.
  • MP > ME owing to the Property of Inequality.
  • MP = PL + LM by the Segment Addition Postulate.
  • MP = LE + LM as derived from statements 1 and 10 using substitution.
  • LE + LM > ME based on statements 9 and 11 and the substitution property of inequality.

Exterior Angle Inequality Theorem

  • The measure of an exterior angle of a triangle is greater than the measure of either remote interior angle.
  • Midpoint Q is on ON, such that OQ ≃ NQ
  • Line MR passes through Q, such that MO ≃ OR
  • OQ ≃ NQ and MQ ≃ QR by construction.
  • ∠3 ≃ ∠4 because they are vertical angles.
  • â–³OQM ≃ â–³NQR per the SAS Congruence Theorem.
  • ∠MON ≃ ∠1 due to CPCTC (Corresponding Parts of Congruent Triangles are Congruent).
  • ∠ONP = ∠1 + ∠2 from the Angle Addition Postulate.
  • m∠ONP > m∠1 using the Property of Inequality.
  • m∠ONP > m∠MON through the Substitution Property.

Hinge Theorem (SAS Triangle Inequality Theorem)

  • If two triangles have two congruent sides, the triangle with the larger included angle has the longer third side.

Converse of Hinge Theorem

  • If two triangles have two congruent sides, the triangle with the longer third side will have a larger angle opposite that third side

Hinge Theorem or SAS Triangle Inequality Theorem

  • If two sides of one triangle are congruent to two sides of another triangle, but the included angle of the first triangle is greater than the included angle of the second, then the third side of the first triangle is longer than the third side of the second.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Use Quizgecko on...
Browser
Browser