u6l3 area of triangles & trapezoids do now: write in planner get out homework to check/grade set...
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U6L3 Area of Triangles & Trapezoids
Do Now:•Write in planner•Get out homework to check/grade•Set up for notes•Find the circumference and area:
Area of a Triangle• The area of a triangle is half the
product of its base b and its height h.
Triangles
• A diagonal of a parallelogram divides the parallelogram into 2 congruent triangles.
• The area of each triangle is half the area of the parallelogram
• The base of the triangle can be any side.
• The height is the perpendicular distance from the base to the opposite vertex.
Practice
**Hint**: multiplying by ½ is the same
as dividing by 2
Area of trapezoids
• The area of a trapezoid is half its height multiplied by the sum of the lengths of its two bases
Trapezoids
• A parallelogram can be divided into 2 congruent trapezoids.
• The two parallel sides of a trapezoid are its bases• A = ½ (b1 + b2)h
Challenge Problem
• Find the missing measurement of each triangle.
• b = 12inh = ?A = 42
42 = ½ b(12)42 = b66 67= b
Assignment
• P. 436-437 #7-9, 13-15, 25