Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
5. Measuring and Constructing Angles
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Exercise 26 Page 44

The sum of the unknown angles is equal to m∠ XYZ.

m∠ XYW=32^(∘)
m∠ WYZ=85^(∘)

Practice makes perfect

The expression m∠ XYW indicates the measure of the angle between two rays, YX and YW. Similarly, the expression m∠ WYZ indicates the measure of the angle between rays YW and YZ. To find their measures, let's start by identifying the three angles on a diagram.

Looking at the figures, and by the Angle Addition Postulate, we can see that m∠ XYZ is equal to the sum of m∠ WYZ and m∠ XYZ. We can solve for x by creating an equation using the expressions for the two smaller angles and the value of the larger angle.
m∠ XYW+m∠ WYZ=m∠ XYZ
(6x+44)+(- 10x+65)=117
6x+44-10x+65=117
- 4x+109=117
- 4x=8
4x=- 8
x=- 2
Having solved the equation, we can calculate the individual angles by substituting x= - 2 into the expressions for the unknown angles. m∠ XYW:& 6( - 2)+44=32^(∘) m∠ WYZ:& - 10( - 2)+65 =85^(∘)