body{margin:0;} noscript{z-index: 10000; position: fixed; display: block; height: 100%; width: 100%; background: #fff;} noscript .fa{font-size: 40px; display:block; color: #daa520;} noscript div{margin-top: 6%; padding-left: 20px; padding-right: 20px; text-align: center;} ! You must have JavaScript enabled to use this site.

Pearson Geometry Common Core, 2011

PG

Pearson Geometry Common Core, 2011 View details

1. Lines and Angles

Continue to next subchapter

Exercise 54 Page 146

Angles ∠ YDF and ∠ YDA are supplementary angles.

m∠ YDA = 59^(∘)

Practice makes perfect

We are given that m∠ YDF=121^(∘). Let's note this information on the diagram.

Now, since ∠ YDF and ∠ YDA form a linear pair we can say that ∠ YDF and ∠ YDA are supplementary angles. Therefore, their measures add to equal 180 ^(∘). m∠ YDF + m∠ YDA = 180^(∘) By substituting 121^(∘) for m∠ YDF into the equation, we can solve for the measure of ∠ YDA.

m∠ YDF + m∠ YDA = 180^(∘)

∠ YDF= 121^(∘)

121^(∘) + m∠ YDA = 180^(∘)

LHS-121^(∘)=RHS-121^(∘)

m∠ YDA = 180^(∘)-121^(∘)

Subtract term

m∠ YDA = 59^(∘)

We found that the measure of ∠ YDA is 59^(∘).

Subchapter links

Lesson Check p.143

Practice and Problem-Solving Exercises p.144-146

Standardized Test Prep p.146

Mixed Review p.146