McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
3. Inequalities in One Triangle
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Exercise 22 Page 431

Use the Triangle Angle Sum Theorem. Then consider Theorem 5.10 about Angle-Side Relationships in Triangles.

Angles: ∠ X, ∠ Y, ∠ Z
Sides: YZ, XZ, XY

Practice makes perfect

On the diagram, we are given the expressions for the interior angles of △ XYZ.

By the Triangle Angle Sum Theorem, we know that the sum of these measures is 180^(∘). (2x+1)+(2x+9)+ 90=180Let's solve it and find the value of x.
(2x+1)+(2x+9)+ 90=180
Solve for x
2x+1+2x+9+ 90=180
4x+100=180
4x=80
x=20
Now that we now the value of x, we can calculate the measures of the angles.
m∠ X = (2x+1)^(∘) m∠ Y = (2x+9)^(∘)
Substitution (2( 20)+1)^(∘) (2( 20)+9)^(∘)
Calculation 41 ^(∘) 49 ^(∘)

Comparing the angle measures, we can see that the smallest angle is ∠ X, followed by ∠ Y and then ∠ Z. m∠ X < m∠ Y Angle-Side Relationships in Triangles.

Angle-Side Relationships in Triangles

If one angle of a triangle has a greater measure than another angle, then the side opposite the greater angle is longer than the side opposite the lesser angle.

Now, by this theorem, we will look for the corresponding opposite sides. cc Angle & Opposite Side [0.5em] ∠ X & YZ [0.5em] ∠ Y & XZ [0.5em] ∠ Z & XY From here, we can list the sides in order from smallest to largest. YZ < XZ < XY