Parallel Lines

  

These square tiles form parallel lines with transversals.  We can use this to demonstrate several theorems and postulates we have learned.

In this special case where the transversal is perpendicular to the parallel lines, all the angle measures are 90.  This means that not only are alternate interior angles supplementary, they are also congruent.

(NW5)

Trapezoids in Candy

This candy piece demonstrates the definition of a trapezoid (specifically an isosceles trapezoid), and Theorem 5-18, which states that the base angles of an isosceles trapezoid are congruent.

Lines AB and DC are parallel while AD and BC are not, which fits the qualification: "A quadrilateral with exactly one pair of parallel sides is called trapezoid." It also fits the qualification of an isosceles trapezoid by having congruent legs. Finally, the candy also fulfills Theorem 5-18, because, as you can see, its base angles are congruent. -IR1

Are We Blind to Parallel Lines?

This image is a picture of the blinds in my bedroom. It is an example of the theorem stating, "In a plane, two lines perpendicular to the same line are parallel." As you can see, line AE and line AF are both perpendicular to line CD. This makes line AE and line AF parallel to each other. - RG1

Perpendicular Lockers

Every day I go to the Morgan Hill Aquatics Center and put my swim bag in the locker rooms there.  We recently got new lockers and while examining them I noticed their perpendicular lines.  As you can see in the picture I put in GSP, I was able to prove that the locker lines formed 90 degree angles where they met.  Therefore, I now know that the lockers have perfect perpendicular lines! ~MG1

Bricks

Bricks are often used for building because they are strong, not only in the sense that they are not easily broken, but also in the sense that if they are staggered in this way then they will not break because they fit together well. They are useful for this purpose because they create the correct amount of total degrees. Rectangles, by definition, have four 90 degree angles. If you put two next to each other, then you will have 180 degrees, making a straight line, which has 180 degrees! Perfect!  ~CB1