Geometry in an Old Sailing Ship

This picture shows an example of perpendicular lines in the ship's sail and mast. There are also examples of an isosceles triangle in the ropes on top. In the middle, there is a crows nest that shows an example of a circle, with the mast going through its center. (~CD1)

Isoceles Triangles

I was at swim practice the other day and I noticed that the backstroke flags were upside down isosceles triangles. Two of the sides of the flags are congruent and the angles opposite to those sides are congruent as well making it an isosceles triangle by the Isosceles Triangle Theorem. (~AD1)

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