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bracing a structure or bridge

E7 Students are expected to recognize, name, describe, and construct right, obtuse, and acute triangles. Just as the rectangle and the circle are very popular in the real world, so is the triangle! You'll find triangles at work:. racking billiard balls. holding up a shelf.

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bracing a structure or bridge

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  1. E7 Students are expected to recognize, name, describe, and construct right, obtuse, and acute triangles

  2. Just as the rectangle and the circle are very popular in the real world, so is the triangle! You'll find triangles at work: racking billiard balls holding up a shelf bracing a structure or bridge

  3. "Cygnet #2, "a tetrahedral kite designed by D. Alexander Graham Bell, built at Baddeck, Nova Scotia, contains 3,960 tetrahedral cells covered with red silk and driven by same motor as the Silver Dart. http://www.digitaloutrider.com/html/bell/inventor.html#silver

  4. A triangle is the simplest polygon, having three sides and three angles. The sum of the three angles of a triangle is equal to 180 degrees.Triangles are classified in two ways: by their sides and by their angles. Equilateral – three sides equal. Side A = Side B = Side C Isosceles – two equal sides Side a equal in length to Side b Scalene – no sides equal

  5. A triangle is named not just from the size of its angles, but also from the lengths of its three sides. A triangle with all sides of the same length is called a(n) triangle. equilateral The angles of this type of triangle are all equal. Since the three angles of any triangle add up to 180 degrees, then each angle in this special type of triangle must be 180 divide by 3 or degrees. 60 = = =

  6. An equilateral triangle has three equal sides. In this type of triangle, the angles are also equal, so it can also be called an equiangular triangle. Each angle of an equilateral triangle must measure 60 degrees, since the sum of the interior angles of any triangle must equal 180 degrees.

  7. An isosceles triangle has just two equal sides, called legs. The third side is called the base. The angles that are opposite the equal sides are also equal.

  8. A triangle with three sides of different lengths is called a scalene triangle. Its angles are all of different sizes, as well.

  9. Now let's classify by angles. An acute triangle has three acute angles, or three angles with a measure of less than 90 degrees. An obtuse triangle has one angle that is greater than 90 degrees. If one of the angles in a triangle is a right angle, then the triangle is called a right triangle. Notice we draw a square at the vertex where the right angle is located. Obtuse – 1 obtuse angle Right – 1 right angle Acute – all three acute angles

  10. You can use two labels for a triangle. For example, triangle MNO is both an acute and an isosceles triangle. Triangle PQR is an obtuse, scalene triangle. Triangle ACB is a right, scalene triangle.

  11. Student Activities • A triangle is a polygon with three sides, three angles, and three vertices. • Examine the different triangles given to you according to the nature of their angles. • Share how you sorted the triangles. • What name is given to each of these triangles when their angle sizes are considered?

  12. Student Activities • Examine the tangram pieces. What is the name of each of the pieces? How many different types of triangles are represented in a set of tangram pieces? • Use geostrips in your group to create as many different triangle types as you can. Sketch your creation using a ruler and then label the triangle with its full name. e.g. right isosceles triangle.

  13. Tangram Pieces How many different types of triangles are represented in a set of tangram pieces?

  14. Student Activities • E7.1 Construct specific triangles on a geoboard and record them on geopaper, e.g., an acute triangle that has one side using five pins, a right triangle that is also isosceles, and an obtuse triangle that has one side using five pins.

  15. Student Activities • E7.2 Draw three examples of each type of triangle. • E7.3 Use two 6cm straws, two 8 cm straws, and two 10cm straws to investigate the triangles that can be made using 3 of the straws at a time. Complete a table of results. • Extension: Use geostrips in your group to create as many different triangle types as you can. Sketch your creation using a ruler and then label the triangle with its full name. e.g. right isosceles triangle.

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