Angles in the Regular PentagonWhat is the angle at any vertex of a regular pentagon? 
Pentagon with 2 DiagonalsThis pentagon is divided into 3 triangles. Compute the measure of all the angles in the figure. 


This pentagon is shown with all its diagonals. Compute the angle measure of all angles in the figure and label the equal angles clearly in the figure.
In the figure, shade in or thicken the outline of a rhombus. How can you be sure that this is a parallelogram? How can you be sure that this is a rhombus? Write down the 4 equal sides of your figure.


Find triangles with these qualities, using the labeled points in the figure above.
Look in the figure of the pentagon with diagonals above. Find a figure like this in which all 3 triangles (the big one and the two subtriangles are isosceles. LABEL the triangle with the letters that correspond to your discovery in the pentagon. JUSTIFY why you can say the 3 triangles are isosceles. What equalities of lengths must be true? 

MAJOR PROBLEM: Let the side of a regular pentagon be s and the length of a diagonal be d, use this figure to find the ratio d/s. (Hint: Is it legit to set s = 1 to simplify?)