Area preteach

Regular Polygons

7- heptagon

8- octagon

9- nonagon

10-decagon

n- n-gon

#of sides

3- triangle

4- quadrilateral

5- pentagon

6- hexagon

#of sides

Names:

Always 360°!

Each exterior angle is 360/n

Ex: triangle?

Ex: pentagon?

Sum of Exterior

(n - 2)(180)

n represents # of sides

Ex: triangle?

Ex: quadrilateral?

Ex: heptagon?

Sum of Interior

Angles in regular polygons:

Multiple Choice

What is the sum of interior angles for a nonagon?

• 1260°

• 1620°

• 180°

• 360°

Multiple Choice

What is the sum of interior angles for a pentagon?

• 540°

• 900°

• 180°

• 360°

Multiple Choice

What is the measure of one of the interior angles in a regular octagon?

• 135°

• 180°

• 360°

• 1080°

Multiple Choice

A hexagon has angles that measure 100°, 157°, 120°, 76°, and 110°. What is the measure of the sixth angle?

• 157°

• 180°

• 54°

• 122°

Area of regular polygons

Vocab:

Apothem- distance from center of shape to midpoint of a side

Perimeter- sum of all side lengths (for regular polygons, all of the side lengths are equal!)

Area of Regular Polygons

1/2 times the apothem times the perimeter

1/2 a P

​

What is the area of the polygon?

Multiple Choice

What is the PERIMETER of the polygon?

• 40 cm

• 8 cm

• 22.5 cm

• 5.5 cm

Multiple Choice

What is the AREA of the polygon?

(use the perimeter you found!)

• 110 cm

• 220 cm

• 22 cm

• 20 cm

Math Xl Q's 4 and 5

Apothem of regular hexagon

If a regular hexagon has a perimeter of 216 cm, what is the length of the apothem?

Multiple Choice

What is the length of the apothem in the regular hexagon?

• 3 $$\sqrt[]{3}$$

• 6 $$\sqrt[]{3}$$

• 36

• 6

Multiple Choice

What is the PERIMETER of the regular hexagon?

• 36 cm

• 6 cm

• 12 cm

• 64 cm

Multiple Choice

What is the AREA of the regular hexagon?

• 93.5 cm

• 187.1 cm

• 36 cm

• 31.2 cm

Math Xl Q 6