The answer is: 12 centimeters.
The explanation is shown below:
1. By definition, all four sides of the square are equal and the diagonals are equal too.
2. Keeping the information above on mind, you know that AC and BD are equal:

3. Then, the length of BD is twice BE. So, you can calculate it as following:


4. Therefore, the lenght of AC is:

draw a rectangle around it:
the widest part is from about -3 to 2 which is 5 units wide
height is from 3 to -4, which is 7 units
5*7 = 35
the top and bottom are angled so you can subtract a little for that
so I would estimate around 32 square units
Angle a = 60
given that all angles of a triangle added together must equal 180
x = -20
-20+80=60
do it again for the other angle measurement
60+60+40=180
therefore, angle A is 60°
Answer: Choice A
S9 = (9/2)*(2+26)
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The formula is
Sn = (n/2)*(a1+an)
where
Sn = sum of the first n terms (nth partial sum)
n = number of terms
a1 = first term
an = nth term
In this case,
n = 9
a1 = 2 (plug in n = 1 into the formula an = 3n-1 and simplify)
an = a9 = 26 (plug n = 9 into the formula an = 3n-1 and simplify)
So,
Sn = (n/2)*(a1+an)
S9 = (9/2)*(2+26)
will help us find the sum of the first 9 terms of this arithmetic sequence
Answer: Did you mean to rewrite that
Step-by-step explanation: