Prentice Hall Geometry

proof Proof of Theorem 7-4: Side-Splitter Theorem

Given: white up pointing triangle q x y  with modified r s with left right arrow above . double vertical bar , modified x y with left right arrow above

Prove: fraction x r , over r q end fraction . equals . fraction y s , over s q end fraction
Triangle QXY has segment RS between sides QX and QY parallel to XY. Angle 1 is at X, angle 2 at Y, angle 3 at QRS, and angle 4 at QSR.

Statements Reasons
1) modified r s with left right arrow above . double vertical bar , modified x y with left right arrow above 1) Given
2) angle , 1 approximately equal to , angle 3 comma   angle , 2 approximately equal to , angle 4 2) If lines are parallel to comma  then corresponding Angles. are approximately equal to .
3) white up pointing triangle q x y , tilde operator white up pointing triangle q r s 3) AA tilde operator  Postulate
4) fraction x q , over r q end fraction . equals . fraction y q , over s q end fraction 4) Corresponding sides of tilde operator  Triangles. are proportional.
5) x q equals x r plus r q comma 5) Segment Addition Postulate
6) fraction x r plus r q , over r q end fraction . equals . fraction y s plus s q , over s q end fraction 6) Substitution Property
7) fraction x r , over r q end fraction . equals . fraction y s , over s q end fraction 7) Property of Proportions (3)

End ofPage 472

Table of Contents

Prentice Hall Geometry Chapter 1 Tools of Geometry Chapter 2 Reasoning and Proof Chapter 3 Parallel and Perpendicular Lines Chapter 4 Congruent Triangles Chapter 5 Relationships Within Triangles Chapter 6 Polygons and Quadrilaterals Chapter 7 Similarity Chapter 8 Right Triangles and Trigonometry Chapter 9 Transformations Chapter 10 Area Chapter 11 Surface Area and Volume Chapter 12 Circles Skills Handbook Reference Visual Glossary Selected Answers Index Acknowledgments