Answer:
Explanation:
Use the Pythagorean theorem to find the length of the missing side that is 1/2 the side of the missing heptagon. You have to assume that the figure is a regular heptagon, something you should point out to your teacher. Math really requires well qualified diagrams.
c^2 = a^2 + b^2
c = 2.77
a = 2.5
b = 1/2 the side of the heptagon.
2.77^2 = 2.5^2 + b^2
7.6729 =6.25 + b^2
7.5629 - 6.25 = b^2
b^2 = 1.4229
b = sqrt(1.4229)
b = 1.1928
But the side is twice that long
s = 2.3857
Now draw another line from the side you just found. It will be the same length as 2.77. It's a radius of the circumcircle.
Area of the triangle so formed is
Area = 1/2 * b * h
b = 2.3857
h = 2.5
Area = 1/2 * 2.5 * 2.3857
Area = 2.982
There are 7 such triangles.
Answer: 7 * 2.982
Answer: 20.87