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Chapter 3. 3-4 Perpendicular Lines. SAT Problem of the day. A cube has a surface area of 6x. What is the volume of the cube? A) B) C) D) E). Solution to the SAT Problem. Right Answer: B. Objectives. Prove and apply theorems about perpendicular lines.
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Chapter 3 3-4 Perpendicular Lines
SAT Problem of the day • A cube has a surface area of 6x. What is the volume of the cube? • A) • B) • C) • D) • E)
Solution to the SAT Problem • Right Answer: B
Objectives • Prove and apply theorems about perpendicular lines.
What is the perpendicular bisector? • The perpendicular bisectorof a segment is a line perpendicular to a segment at the segment’s midpoint.
Distance from a point to a line • The shortest segment from a point to a line is perpendicular to the line. This fact is used to define the distance from a point to a lineas the length of the perpendicular segment from the point to the line.
Example#1 A. Name the shortest segment from point A to BC. The shortest distance from a point to a line is the length of the perpendicular segment, so AP is the shortest segment from A to BC.
Example#1 • B. Write and solve an inequality for x. • AC > AP • x – 8 > 12
Example#2 A. Name the shortest segment from point A to BC. AB is the shortest segment from A to BC. B. Write and solve an inequality for x. AC > AB 12 > x – 5
Student guided practice • Do problems 2 and 3 from your book page175
HYPOTHESIS CONCLUSION
Proving perpendicular lines • Write a two-column proof. • Given: r || s, 1 2 • Prove: r t
solution 1. Given 1.r || s, 1 2 2. Corr. s Post. 2.2 3 3.1 3 3. Trans. Prop. of 4. 2 intersecting lines form lin. pair of s lines . 4.rt
Given: Prove: Proving perpendicular lines • Write a two-column proof.
2. 3. 4. 1. Given 1.EHF HFG 2. Conv. of Alt. Int. s Thm. 4. Transv. Thm.
Student guided practice • Do problem 4 in your book page 175
Homework • Do problems 6- 8,12-15 in your book page 175 and 176
closure • Today we learned about perpendicular lines • Next class we learned about slopes of lines