Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
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Exercise 10 Page 211

The Triangle Angle Sum Theorem tells us that the sum of the angle measures of any triangle will be 180^(∘).

x=40
Angle Measures: 80^(∘), 64^(∘), 36^(∘)

Practice makes perfect

We can use the given algebraic expressions for the angle measures of a triangle to find the numeric measures of these angles. 2x, x+24, x-4 The Triangle Angle Sum Theorem tells us that the sum of the angle measures of any triangle will be 180^(∘).

m ∠ A+m ∠ B+m ∠ C=180 Applying this theorem, we can write an equation for the sum of the angle measures of our triangle. (2x)+(x+24)+(x-4)=180 Now, let's solve this equation for x.
(2x)+(x+24)+(x-4)=180
Solve for x
2x+x+24+x-4=180
4x+20=180
4x=160
x=40
The value of x is 40. Next, we can substitute 40 for x into the algebraic expressions to find the angle measures for our triangle. ccccc Expression & & x= 40 & &Angle [0.5em] 2x & ⇒ & 2( 40) & ⇒ &80 x+24 & ⇒ & 40+24 &⇒ &64 x-4 & ⇒ & 40-4 &⇒ &36 We can check our answer by substituting the angle measures into the equation created by the Triangle Angle Sum Theorem.
m∠ A+m∠ B+m∠ C=180
80+64+26? =180
180=180 ✓
Since we have an identity, our solution is correct.