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Ilia_Sergeevich [38]
3 years ago
7

Explain how the sum and difference formula cos(A+/- B) = cosA cosB -/+ sinA sinB could be useful?

Mathematics
2 answers:
Nadya [2.5K]3 years ago
7 0
You could find the exact value of cos of 15 degrees   by  using cos(45 - 30):-

cos(45 - 30) = cos 45cos30 + sin45 sin30  = 1 /sqrt2 * sqrt3/2 +  1/sqrt2* 1/2 
serg [7]3 years ago
6 0
One way it's useful is in the application of phasors in physics. Phasors require you to add up vectors of two different angles, so the cosine angle addition formula can be used if you already know the cosine and sine of the original vector angles.
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the area of a triangle is 124 square units. what would it's new area be if its base was half as long and its height was three ti
Montano1993 [528]
To solve this problem you must apply the proccedure shown below:

 1. You have that the formula for calculate the area of a triangle is:

 A=bh/2

 Where A is the area of the triangle, b is the base of the triangle and h is the height of the triangle.

 bh/2=124
 bh=124x2
 bh=248

 2. The problem asks for the new area of the triangle <span>if its base was half as long and its height was three times as long. Then, you have:

 Base=b/2
 Height=3h

 3. Therefore, when you substitute this into the formula for calculate the area of a triangle, you obtain:

 A'=bh/2

 (A' is the new area)

 A'=(b/2)(3)/2
 A'=3bh/4

 4. When you substitute bh=248 into </span>A'=3bh/4, you obtain:
<span>
 A'=186 units</span>²
<span>
 The answer is: </span>186 units²
3 0
3 years ago
Check all that apply. is the reference angle for:
3241004551 [841]

Answer:

B. C. and D.

Step-by-step explanation:

4 0
2 years ago
A radioactive substance decays exponentially. A scientist begins with 100 milligrams of a radioactive substance. After 27 hours,
never [62]
33.3 because 27/50=36/x and x=66.67 and thats how much as decayed after 36 hours but you want what is left so subtract from 100 and get 33.3
7 0
3 years ago
What is five times three hundred
spayn [35]
The answer is 1500 I hope this help!
4 0
3 years ago
Plsss help me this is due Friday:{
prisoha [69]

Answer:

1.) subtract = 1 1/3 - 3 1/2 = answer

2.) subtract = 6 3/4 - 1 1/2 = answer

3.) add = 3 1/4 + 2 1/8= answer

4.) subtract = 4 3/4 - 2 1/6 = answer

Step-by-step explanation:

5.) 3 lawns = 6 3/4 hrs

1st lawn 2 1/2 hrs

2nd lawn 1 3/4 hrs

add 2 1/2  + 1 3/4 = total

then 6 3/4 hrs - total = the amount it takes to mow the 3rd lawn

im sure u know how to add and subtract fractions is u r in middle school :)

7 0
3 years ago
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