The value of the given trigonometry function is 2√15/15
<h3>Half angles</h3>
Half angles are trigonometric identities used to express sine, cosine and tangent of half angles.
For instance the value of cos theta is expressed as shown below;
cosФ = cos(Ф/2+Ф/2)
cosФ = cos²Ф/2-sin²Ф/2
cosФ = cos²Ф/2-(1-cos²Ф/2)
cosФ = 1 - 2cos²Ф/2
Given the following parameters
cosФ = -7/15
Substitute
cosФ = 1 - 2cos²Ф/2
-7/15 = 1 - 2cos²Ф/2
-2cos²Ф/2 = -7/15 - 1
-2cos²Ф/2 = -8/15
cos²Ф/2 = 4/15
cosФ/2 = 2/√15
Rationalize
2/√15 * √15/√15
2√15/15
Hence the value of the given trigonometry function is 2√15/15
Learn more on trigonometry function here: brainly.com/question/2254074
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The percentage change is 20%
Given:
1 inch : 18 kilometers
Let us use the ratio and proportion method:
a:b = c:d where ad = bc
0.8 inches is <u>14.4 kilometers</u>
1 : 18 = 0.8 : x
x = 0.8 * 18
x = 14.4 km
1.4 inches is <u>25.2 kilometers</u>
1: 18 = 1.4 : x
x = 18 * 1.4
x = 25.2 km
2.1 inches is <u>37.8 kilometers</u>
1 : 18 = 2.1 : x
x = 18 * 2.1
x = 37.8 km
Let h = the number of horses in the field
Let c = number of cows in the field
There are 2 more horses than cows in the field. Therefore
h = c + 2
or
c = h - 2 (1)
There are 15 animals in the field. Therefore
h + c = 15 (2)
Substitute (1) into (2).
h + (h - 2) = 15
2h - 2 = 15
Answer:
The correct equation is
2h - 2 = 15
