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.

McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

4. Rectangles

Continue to next subchapter

Exercise 28 Page 509

Notice that ∠ 2 and ∠ 3 form alternate interior angles.

m∠ 3=40

Practice makes perfect

Let's analyze the given quadrilateral so that we can find the measure of ∠ 3.

Notice that ∠ 2 and ∠ 3 form alternate interior angles. Because our quadrilateral is a rectangle, both pairs of opposite sides are parallel. Recall the following theorem.

Alternate Interior Angles Theorem
If parallel lines are cut by a transversal, then the pairs of alternate interior angles are congruent.

Therefore, by the ∠ 2 and ∠ 3 are congruent and their measures are equal. m ∠ 2=m ∠ 3 We already know that m ∠ 2= 40. Therefore, m ∠ 3= 40 as well.

Subchapter links

Exercises p.508-511