The document discusses using trigonometry to find the areas of regular polygons and triangles. It explains that the area of a regular polygon can be found when the length of its sides is known, and the area of a triangle can be found by knowing two sides and the included angle. Examples are provided for finding the areas of a regular pentagon, decagon, and triangles using trigonometric functions. Students are assigned homework problems applying these area formulas.

2. Essential Understanding
 You can use trigonometry to find the area of a
regular polygon
 You can use trig to find the area of a triangle when
you know the length of two sides and the included
angle.
 Students will be able to find areas of regular
polygons and triangles using trigonometry.

3. Find the Area of the
Nonagon

4.  What is the area of a regular pentagon with 4in
sides? Round your answer to the nearest square in.
 A tabletop has the shape of a regular decagon with a
radius of 9.5 in. What is the area of the tabletop to
the nearest square inch?

5. Finding Area
 Suppose you want to find the area of a triangle.
What formula could you come up with to find the
area of any triangle using a trig function
 sinA = h/c
 h = csinA
 A = ½(bc)sinA

6. What is the area of the
triangle

7. What is the area of the
Triangle?

9. Homework
 Pg. 646
 #6 – 28 even, 36, 45 – 47
 16 problems