Answer:
C) 
Step-by-step explanation:
By the cos double angle formula, we know 
Substituting 
into the formula, we get
.
The answer is C.
Answer:
13
Step-by-step explanation:
Here's a method of finding the area of any polygon knowing its vertices. I'm using this parallelogram as an example.
Make a table like this (each vertex with its x- and y-coordinates):
Pt x y
A 3 6
B 6 5
C 5 1
D 2 2
A 3 6
Now multiply each x-coordinate by the y-coordinate on the line below and write it on the right side. Bold type shows the first multiplication.
x y
A 3 6
B 6 5 15
C 5 1 6
D 2 2 10
A 3 6 12
Now multiply each y-coordinate by the x-coordinate on the line below and subtract from each produce you already have. Do each subtraction. Bold type shows the first multiplication.
x y
A 3 6
B 6 5 15 - 36 = -21
C 5 1 6 - 25 = -19
D 2 2 10 - 2 = 8
A 3 6 12 - 6 = 6
Add all the differences.
x y
A 3 6
B 6 5 15 - 36 = -21
C 5 1 6 - 25 = -19
D 2 2 10 - 2 = 8
A 3 6 12 - 6 = 6
+____
-26
The area of the polygon is the absolute value of half of the sum of the differences.
area = |-26/2| = |-13| = 13
Answer:
Step-by-step explanation:
The perpendicular is equal to 6. That's because the left triangle's missing angle is 180 - 45 -90 = 45
The angle in the right triangle is given as 52.
The cos(52) = adjacent side (which we just found to be 6) / y
Multiply both sides by y
y cos(52) = 6
cos(52) = 0.6157
Divide by sides by cos(52)
y = 6 / cos(52)
y = 6 / 0.6157
y = 9.76
The answer for your question is Option C. Kilometers
