Draw to lines in your notebook line the ones below. What is true about the lines?

Draw to lines in your notebook line the ones below. What is true about the lines?

THEY ARE PARALLEL. MARK THEM.

Draw a transversal. A transversal is a line that intersects two other lines.

Label the intersection points A & B.

Draw another transversal that intersects B.

What angles are equal in this picture? You do not have to write this down.

Write this down. 1 5 since they are corresponding angles.

Draw another transversal that intersect point B. What is a transversal again?

Draw another transversal that intersect point B. What is a transversal again?

Which angle is congruent to 9?Why?

Which angle is congruent to 9?Why?

9 11 since they are corresponding angles. Write this down.

9 11 since they are corresponding angles. Mark this in your diagram.

Are there other angles that are congruent?

15 16 because they are vertical angles.

What does this justify or prove? NCTM

THE SUM OF THE ANGLES IN A TRIANGLE ADD TO 180

Website regarding triangleshttp://argyll.epsb.ca/jreed/math9/strand3/3103.htmhttp://www.ies.co.jp/math/java/geo/san180/san180.html

Practice Problems:

HW

Triangles in Architecture

New design for a building in London; has not been completed yet.

Hearst Tower in Manhattan, New York

Close up view of the Hearst Tower.

The inside of a dome.

Truss bridges use the triangle — a very stable shape — to distribute load forces.

Howrah Bridge spans over the Hooghly River in West Bengal, India.

The Little Belt Bridge also known as The Old Little Belt Bridge, is a truss bridge over the Little Belt strait in Denmark.

The pyramids of Giza in Cairo, Egypt

Unitarian Meeting House built by Frank Lloyd Wright in Madison, Wisconsin.