# Q3, W8: Geometry (February 25-March 1) Teacher Kristin Andreason Geometry Honors 8 Eight Unit 6: Two-Dimensional Measures
Standard(s) Taught

MAFS.912.G-GMD.1.1:  Give an informal argument for the formulas for the circumference of a circle, area of a circle, volume of a cylinder, pyramid, and cone. (Use dissection arguments, Cavalieri’s principle, and informal limit arguments.)

Learning Targets and Learning Criteria
• define regular polygons.
• inscribe a regular polygon in a circle and break it into many congruent triangles to find its area.
• explain and use the dissection method on regular polygons to generate an area formula for regular polygons A = ½ × apothem × perimeter (A = aP).
• calculate the area of a regular polygon A = ½ × apothem × perimeter   (A = ½aP).
• use pictures to explain that a regular polygon with many sides is nearly a circle, its perimeter is nearly the circumference of a circle, and that its apothem is nearly the radius of a circle.
• substitute the “nearly” values of a many sided regular polygon into   A = ½ × apothem × perimeter (A = ½aP) to show that the formula for the area of a circle is A = πr2.
Classroom Activities

Monday/Tuesday:

• Finish Real-Life Area of Compound Figures (2nd period)
• Area of regular polygons notes, graphic organizer, and foldable
• Start area of regular polygons scavenger hunt

Wednesday:

• Continue working on Area of regular polygons scavenger hunt

Thursday/Friday:

• Finish the area of regular polygons scavenger hunt
• Do the Real Life challenge question
Assignments Due
• Area of regular polygons scavenger hunt due on March 1st.