Answer:
B
Step-by-step explanation:
Euler's formula for polyhedra states that
F + V - E = 2
where F is faces, V is vertices and E is edges
Substitute the values given and solve for F, that is
F + 13 - 26 = 2
F - 13 = 2 ( add 13 to both sides )
F = 15 → B
Answer:
See below.
Step-by-step explanation:
This is how you prove it.
<B and <F are given as congruent.
This is 1 pair of congruent angles for triangles ABC and GFE.
<DEC and <DCE are given as congruent.
Using vertical angles and substitution of transitivity of congruence of angles, show that angles ACB and GEF are congruent.
This is 1 pair of congruent angles for triangles ABC and GFE.
Now you need another side to do either AAS or ASA.
Look at triangle DCE. Using the fact that angles DEC and DCE are congruent, opposite sides are congruent, so segments DC and DE are congruent. You are told segments DF and BD are congruent. Using segment addition postulate and substitution, show that segments CB and EF are congruent.
Now you have 1 pair of included sides congruent ABC and GFE.
Now using ASA, you prove triangles ABC and GFE congruent.
Answer:

Step-by-step explanation:
Given
See attachment
Required
The area of the semicircle
First, we calculate the hypotenuse (h) of the triangle
Considering only the triangle, we have:
--- cosine formula
Make h the subject



The area of the semicircle is then calculated as:

This gives:



Answer:
Step-by-step explanation:
x = 5
x= -4