Answer:
Part 1) The length of the apothem is 13.32'
Part 2) The perimeter of the decagon is 86.5'
Step-by-step explanation:
we know that
A regular decagon has 10 equal sides and 10 equal interior angles
A regular decagon can be divided into 10 congruent isosceles triangle
(they are isosceles since their two sides are the radii of the polygon and the unknown side is the side of the polygon)
The vertex angle of each isosceles triangle is equal to

To find out the side length of the decagon, we can use the law of cosines
so

where
c is the length side of decagon
a and b are the radii
we have

substitute the values




To fin out the perimeter of decagon multiply the length side by 10
so

To find out the apothem we can apply the Pythagorean Theorem in one isosceles triangle
see the attached figure to better understand the problem

substitute the given values

solve for a


Answer:
- Yolanda is 28
- Zachary is 21
Step-by-step explanation:
Let y represent Yolanda's age now, and let d represent their difference in ages. Then Zachary is now y-d years old.
When Yolanda was Zachary's age (now), Zachary was (y-d) -d. Yolanda is now twice that age:
y = 2(y -2d)
4d = y . . . . . . eliminate parentheses, add 4d-y
__
When Zachary is as old as Yolanda is now, Yolanda will be y+d and the sum of their ages will be 63:
y + (y+d) = 63
2y + d = 63
Using the expression for y from above, we get ...
2(4d) +d = 63
d = 7 . . . . . . . . divide by 9
y = 4d = 28 . . . . Yolanda's current age
y-d = 21 . . . . . . . Zachary's current age
I added all of the distances together and got 47.5